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Asimov
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Solar system and back
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THE SOLAR SYSTEM AND BACK
ESSAYS
ON SCIENCE
by Isaac Asimov
ONLY A TRILLION FACT AND FANCY
VIEW FROM A HEIGHT ADDING A DIMENSION
OF TIME AND SPACE AND OTHER THINGS
FROM EARTH TO HEAVEN IS
ANYONE THERE?
SCIENCE NUMBERS AND
I
THE SOLAR SYSTEM AND BACK
THE SOLAR SYSTEM AND BACK BY ISAAC ASIMOV
volume are reprinted from The Magazine of Fantasy and Science Fiction. Individual essays appeared in the following issues: All essays in this
Nothing
The First Metal The Seventh Metal The Predicted Metal The Seventh Planet The Dance of the Sun Backward, Turn Backward— Counting Chromosomes Little Lost Satellite
The Terrible Lizards The Dying Lizards Little Found Satellite The Planetary Eccentric View from Amalthea The Dance of the Satellites Uncertain, Coy, and Hard to Please Just Right The Incredible Shrinking People
©
March, 1959 December, 1967 January, 1968 February, 1968 March, 1968 April, 1968 May, 1968 June, 1968 July, 1968 August, 1968 September, 1968 October, 1968 November, 1968 December, 1968 January, 1969 February, 1969 March, 1969 April, 1969
1959, 1967, 1968, 1969 by Mercury Press, Inc.
Library of Congress Catalog Card
Copyright
©
Number: 78-
1970 by Isaac Asimov
All Rights Reserved Printed in the United States of America
To—Howard
Gotlieb,
curator extraordinaire
19& 1840
Digitized by the Internet Archive in
2011
http://www.archive.org/details/solarsystembackOOasim
CONTENTS INTRODUCTION
I
ix
- THE SOLAR SYSTEM A
— 1
2 3
4
B
— 5
6 7 8
The Inner System
— — — —
THE SEVENTH PLANET
5
THE DANCE OF THE SUN
lO.
BACKWARD, TURN BACKWARD—
33
LITTLE LOST SATELLITE
47
The Outer System
— — — —
LITTLE FOUND SATELLITE
63
VIEW FROM AMALTHEA
77
THE DANCE OF THE SATELLITES
91
THE PLANETARY ECCENTRIC
IO4
AND BACK
II
A
— 9 10
Physics
— —
JUST RIGHT
123
THE INCREDIBLE SHRINKING PEOPLE
136
THE SOLAR SYSTEM AND BACK
Vlll
B
— 11
12 13
C — 14 15
16 17
Chemistry
— — —
THE FIRST METAL
151
THE SEVENTH METAL
164
THE PREDICTED METAL
1JJ
Biology
— — — —
THE TERRIBLE LIZARDS
191
THE DYING LIZARDS
205
COUNTING CHROMOSOMES
2l8
UNCERTAIN, COY, AND HARD TO PLEASE
232
INTRODUCTION
Writing the essays that
fill
this
book and
its
predecessors,
and
appearing in book form, are to be found in each
that, prior to
The Magazine of Fantasy and Science Fiction, has certain game to me. The game is this: I do my best to treat a subject accurately and
issue of
aspects of a
concisely
and the readers do
The readers I make the
their best to catch
is
happened more than twice cases.
want
errors.
a disaster that precludes republication of
a particular essay altogether, but I'm
I
out in
necessary corrections in public.
Occasionally, there
now
me
often score points, though rarely disastrous ones, and
to take
Where can
I
happy
to say that hasn't
in over ten years of essay writing,
back the adverse decision
do
this better
in
and
one of those
and more happily than
in the
introduction to one of these collections?
The
essay in question appeared in early 1959.
Here
it is:
NOTHING The word "vacuum" comes from "empty."
(We
the Latin vacuus, meaning
run close to the original in nonscientific lingo, too,
THE SOLAR SYSTEM AND BACK
X as is
when we empty This
in theory,
is fine,
we mean
a
is
accustomed
vacuum
"vacuous stare.") Consequently, a vacuum
talk of a
space, or space that contains nothing.
and we
volume of space with
to.
The
question
Or, to put
exist?
less
matter in
we
than
it
Does a
though:
is,
another way:
it
vacuums when
talk easily of
true,
all
are
ideal
there such a thing
Is
as nothing?
In between atoms of a gas there sense (there
may be
is
no matter
in the ordinary
we can
speak
raise ourselves
above
stray electrons or neutrinos) so
of an "interatomic vacuum." However,
if
we
the atomic level and consider a reasonable volume of the universe, say a cubic centimeter,
then the question of a vacuum
grows more interesting.
For instance, at
sea-level pressure
and 20
C.
(68° F.), air
has a density of 0.0012 gram per cubic centimeter. This means that every cubic centimeter contains 2.5
gen and nitrogen. Almost
X
10 19 molecules of oxy-
the mass of the molecules
all
is
in the
protons and neutrons (together called nucleons) in the nuclei of
the atoms making them up.
The oxygen molecule
contains 32
nucleons and the nitrogen molecule has 28. There are four nitro-
gen molecules for every oxygen molecule in the atmosphere, altogether, ordinary air contains 7.25
X
10
20
so,
nucleons per cubic
centimeter.
In the laboratory,
from which nearly
it is
all
possible to prepare a
the air has been evacuated. This
is
called
of
only about a ten-billionth the original quantity.
That's not bad, you understand, but even such a
vacuum
is
man-made vacuums the amount
a vacuum, and in very good air left
volume of space
retains
about 7.25
X
10
10
man-made
nucleons per cubic centimeter.
That's nearly a hundred billion nucleons in every cubic centimeter
and that sounds
Of times
as
though
there's
still
course, the science-fiction reader this.
After
all,
thins out,
There as
and
is
a bit of
knows
crowding going on.
a trick worth several
always the "vacuum of outer space."
we move up away from at a height of
the Earth, the atmosphere
200 miles or
so, it
becomes
a
vacuum
INTRODUCTION that
is
at least as
a height
still
good
as
any we can make in the laboratory, and at
vacuum
greater, the
propriate jargon,
it is still
is still
is
is
vacuum com-
a fine
we can manage,
pared to the miserable specimens
from nothing. There
better (or to use the ap-
"harder").
But even though interplanetary space far
XI
it
is
still
the debris left over from the dust and
gas out of which the solar system was formed. In fact, even in
the vast reaches between the
interstellar space,
from the
debris left over
still
formation of the raise
Sun
stars.
The
there
stars,
is
and gas used in the matter is thick enough to
original dust
interstellar
obscuring black clouds out in the galactic arms, where our
compared
located and where most of the dust exists (as
is
with the comparatively dustless galactic center).
The
case
is
similar for other galaxies.
The
average density of matter in interstellar space
is
io~ 21
gram per cubic centimeter according to some (necessarily rough) estimates I have seen. This would amount to only 1000 nucleons per cubic centimeter. Interstellar space is a vacuum that is nearly a hundred million times as hard as any we can manage but it obviously isn't nothing.
we have one more
Still,
trick to play.
dous distances between the
What
about the stupen-
galaxies, distances that
dwarf the
al-
ready tremendous stretches between the stars within a galaxy. Surely, intergalactic space
space—and
But
yet,
omers
still
ought to be emptier than
even intergalactic space
is
not quite nothing. Astron-
enough
detect
some matter
there,
light reaching us
from distant
galaxies.
But it?
intergalactic space
if
The
interstellar
it is.
is
not nothing,
to leave its
how
mark on
near nothing
is
lowest figure I've seen for the density of the matter in
intergalactic space
is
(and again
I
warn you,
it's
only a rough
approximation) io~ 24 gram per cubic centimeter. This amounts to just
This (or,
about is
1
nucleon per cubic centimeter.
as close to
nothing as anything in the universe ever gets
perhaps, ever can get).
It's
so close to nothing that
it
would
THE SOLAR SYSTEM AND BACK
XU
seem
at
about
But can we
forget about it? Is
it
so close to nothing,
it
doesn't
and we needn't confine ourselves to pinches size of the Earth and imagine
large
is
Suppose we take a volume the
The Earth
with intergalactic matter.
it filled
ber of cubic centimeters, to be sure— 1.1
There would be of these
The
mass of
up
takes
X
io
27 ,
num-
a large
to be exact.
nucleon for each of those and the total mass
1
would come to 1800 grams (4 pounds).
Sun, with a volume that
Earth, would,
if
composed of
1,300,000 times that of the
is
contain a
intergalactic material,
109 grams or 2600 tons.
X
2.3
However, ter
nothing and forget
see.
space
First, it.
just call it
it.
matter? Let's
of
we can
glance that
first
unfair to try to get an idea of intergalactic mat-
it is
by using such small units of volume. The Earth, and even the
Sun, are submicroscopic dots compared to the universe, and their
volumes are beneath contempt.
We
have
space to consider. In measuring distances outside
all
our solar system, the smallest useful unit
years as the
cube which
A
minimum
unit.
is
the light-year. Surely,
we ought
then, in measuring spatial volume,
(A cubic
to use cubic light-
light-year
is,
light-year, or 9.5 trillion kilometers,
is 1
cubic light-year contains 8.5
of course, a
on each
side.)
10 53 cubic centimeters.
X
One
nucleon for each of that vast number of cubic centimeters comes
X
to a mass of 1.4
io 30 grams or 1.5
X
10 24 (one
and
a half
tril-
hard vacuums,
this
lion trillion) tons.
Now we have nothingest of trillions
of tons
And,
after
man
standpoint,
all,
something! This hardest of
all
nothings,
when
a
still
piles
volume of
really
in the trillions of
a cubic light-year
a cubic light-year, large as is
all
up matter it is
is
involved.
from a merely hu-
an insignificant fraction of the volume
of the universe.
To show you what
I
mean, consider that the 200-inch telescope
can penetrate over a billion light-years in every direction and, as
INTRODUCTION we can
far as
no way of let's
Xlii
see or photograph, galaxies stretch out.
telling yet
how much
There
is
further the universe reaches but
imagine a sphere with ourselves at the center and a radius
of a billion light-years. We'll content ourselves with this
doubt, tiny) fraction of
With
and
all
call it
(no
the "observable universe."
a radius of a billion (io 9 ) light-years, the
volume of the
observable universe can be calculated easily enough. It turns out
You a
io 27 (four thousand
X
to be 4
trillion trillion)
was right in saying that a
see, I
mere yawn-worthy speck. (Not all the universe is intergalactic
consists of the galaxies themselves.
only a tenth of a per cent of
all
cubic light-years.
single cubic light-year
is
really
some of it make up we can ignore them at
space, of course;
However, the
space, so
galaxies
this point.)
At the
rate of 1 nucleon per cubic centimeter, the
amount
of
matter in the intergalactic space of the observable universe comes
X
to 5.6
io 57 grams.
This sounds
and 5,600,000,000,000,000,000,000,000,-
like a lot,
000,000,000,000,000,000,000,000,000,000,000 grams
much is it
age
is it,
comparison to the mass of a
in
star,
X
has a mass of 2
much more
weighs
amount
is
though, on a universal scale? For instance:
than a
star?
How How much
a lot.
Our own Sun, an
aver-
io 33 grams, so the intergalactic matter star;
much, much more. In fact, the mere couple of thousand
of intergalactic matter in a
cubic light-years equals the mass of the Sun.
However, the Sun about a hundred stars in
the galaxy
is
only one of many.
billion
(io
11 )
Sun's mass to be the average for see,
stars.
therefore about 2
is
stars,
Our
galaxy contains
The total mass of all X io44 grams, assuming which
it
probably
is.
the the
As you
the intergalactic matter weighs more than the stars in an
entire galaxy;
much
But our galaxy verse,
it
is
is
more. also only
one of many. In the observable uni-
estimated that there are about a hundred billion
(io 11 ) galaxies. universe
is
The
total
therefore 2
X
mass of io
55
all
grams.
the stars in the observable
THE SOLAR SYSTEM AND BACK
XIV
So, as sive,
it
turns out, the intergalactic matter
more massive than
as massive,
if all
all
the stars in
all
is
still
more mas-
the galaxies— 280 times
the round approximations
I
have used are con-
sidered accurate.
In fact, a godlike creature from outside our universe, looking over the entire business with a casual eye, would be justified in describing
it
as
He would
be
the occasional dots of non-vacuum, as
we
nothing more than a hard vacuum.
just as right to ignore
when we
are in ignoring dust particles
describe our atmosphere as
a gas.
vacuum of intergalactic space nothing? Heck, no! If we consider only quantity— it is Is
the
practically every-
thing.
After this appeared, friend of
mine who
intergalactic gas
received a letter from a
I
me
told
was
far too
that
my
young astronomer
estimate of the density of the
high on the basis of recent data and
that the mass of dispersed intergalactic matter was probably not
more than the
2 per cent that of the galaxies.
I
sighed,
and
retired
article.
And
then, in early 1968, nine years after the article was written,
new evidence turned
up.
By measuring X-ray
from rockets above the atmosphere, Proving Ground,
New
prising quantity of hot
fluxes in outer space
scientists
at
White Sands
Mexico, decided there could well be a
hydrogen
In fact, they say, "there
sur-
in intergalactic space.
may be one hundred
times as
much
matter dispersed as a gas in the vast reaches of space between galaxies as there
is
in all the
mass of
all
is
not yet as high as the figure
I
arrived at
figuring,
ror
the galaxies combined."
by guess and by and the initial X-ray evidence may turn out to be in eror to be misleading. Still, it is enough to make me bring my
This
old article out of retirement.
And
to
make me
feel very
good, too.
THE SOLAR SYSTEM
A
— THE
INNER SYSTEM
THE SEVENTH PLANET
1
Every once in a while, as
my
blooper in one of
my
Gentle Readers know,
essays. In that case, a
write Gently to say: "Doesn't five plus four
Then
said eight!"
To
err
is
correct
an
article
a mistake.
make
A
of Readers
nine?
You
to correct gently
comes a time when
it
is
humane.
is
necessary for
me
because scientists have discovered they had
Then, unaccountably,
am
I
furious.
How
to
made
dare they
a mistake!
case
about
also
pull a
correct myself with an embarrassed giggle.*
I
human, and
But there
number come to
I
it
happened a couple of
years ago
and Tve been brooding
my essay "Round and Round and—" (which Of Time and Space and Other Things, Doubleday, made the casual statement: "Both Mercury and Venus
ever since. In
appeared in 1965),
I
turn one face eternally to the Sun.
That was
knew when is
exactly right as far as
I,
.
or anyone else in the world,
that article was written (in mid-1963 actually), but
no longer
the back of
." .
right.
it
Astronomers have changed their minds, and
my hand
to them.
They not only outdated an
but also two novels and one novelette that * See, however, the Introduction, in case
I
you skipped
article,
had written with it.
THE SOLAR SYSTEM AND BACK
6
Have they no heart? wind indeed, out of which I cannot make an
painstaking attention to scientific accuracy.
But
it is
essay,
and
some
detail.
an
ill
time
it is
As
now
for
is
deal with the seven planets
The Greeks to
stars,
among
be
Of
these
situation in
will begin at the beginning and
known
to the ancients.
and therefore included the Sun and
number. The remaining
more
Moon
which are bright
five,
star-
or less easily visible to the naked eye, are Mars,
Venus, and Mercury.
Jupiter, Saturn,
is.
I
new
to consider the
considered any body that moved, relative to the
a planet,
their
like objects
me
usual for me,
five,
three are farther from the
Sun than the Earth
This means that they move in great swings about Sun and
Earth
They can each
alike.
them be
of
between them and the Sun.
is
directly
is
at the zenith
when
the Sun
is
any bright
night
is
The
starlike object
is
this
is so,
on the other
at nadir
Earth. This means that the planet viously,
so placed that the Earth
When
the planet side of the
at zenith at midnight.
which
is
Ob-
high in the sky at mid-
easy to observe.
Venus and Mercury, which are is. They can never be in such a position that the Earth is directly between them and the Sun, because the Earth would then have to be closer to the Sun than they are and that is not so. This means that Venus and Mercury case
is
quite different for
Sun than the Earth
closer to the
can never be seen in the night sky at the zenith. It is
can happen, on the other hand, that either Venus or Mercury
more
and the Sun. This is and each planet is then closer to the other times. Venus will be as close to us as
or less directly between the Earth
called "inferior conjunction"
Earth than
it
ever
is
at
25,000,000 miles and Mercury as close as 49,000,000. trouble
is
look in the direction of the Sun and everything
Of Sun, side
course, it
The only we must
that in that case, in order to see either planet
will
if
either planet
is
is
lost in
the glare.
exactly between ourselves
show up against the Sun's
disk.
But then
away from us (and toward the Sun) that
is
lit
and the it
is
the
by sunlight,
THE SEVENTH PLANET and
all
we
see
7
the black disk of the night side against the bright-
is
ness of the Sun.
But travels
let's
Venus
concentrate on
about the Sun.
We can
to begin with,
start
with
it
and follow
its
at inferior conjunction
between ourselves and the Sun. Steadily, as
Sun.
moves in its orbit, Venus pulls away from the and in the same direction, but Venus moves
it
(We move
also,
more quickly than Earth does, being closer to the Sun's pull.) As moves away, we can see around the night side a trifling bit and
it
the edge of the sunlit side (as seen through a telescope) looks like a thin crescent.
The farther it gets away from the Sun, the more of the sunlit we can see and the thicker the crescent. Finally, the imaginary
side
Venus
line connecting
to the
the imaginary line connecting
Venus
Sun comes to be at right angles to Venus to the Earth. We then see
"in profile" so to speak. Half of the face
the other half
is
The
dark.
planet
is
we
see
is
sunlit,
in the "half-Venus" phase
(see Figure 1).
Let's freeze matters at this half-Venus phase for a while.
point in
its orbit,
distance of 47
Venus
is
planet
"maximum
at
as far as
Now let's go on in its orbit,
it
At
this
separated from the Sun by an angular
viewed from Earth).
(as
station, this is
is
Venus can
From our
earthly viewing
The
possibly get from the Sun.
elongation."
and allow Venus
to
move
again.
As
it
continues
begins to curve away from us and back toward the
Sun.
We see
more and more of the
sunlit side as
far side of its orbit, until just before it passes
side
toward us
could see
it
is
at
fully
all,
lit
up.
it
moves along the
behind the Sun, the
We would then see "full-Venus"
which we couldn't,
have to look directly at the Sun to see
for it.
if
we
once again we would It is
now
at "superior
conjunction."
But then
it
moves away from the Sun
changing from full-Venus back to at half- Venus
it is
at
maximum
in the other direction,
half-Venus as it goes.
elongation again, 47
,
When
it is
but on the
THE SOLAR SYSTEM AND BACK Figure
1
Orbit and Phases of Venus
AT SUPERIOR CONJUNCTION AT MAXIMUM ELONGATION AT MAXIMUM BRIGHTNESS 4. AT INFERIOR CONJUNCTION
1. 2.
3.
other side of the Sun. Again a narrowing crescent until
moves toward the Sun, becoming directly between us and the Sun
it
it is
again. Let's see
what
a 47
maximum
makes one complete turn through 15
in
1
360 (
)
elongation means.
in 24 hours,
hour. It turns through 47
The Earth
and therefore turns in 3 hours
and 8
minutes.
Suppose, then, that Venus
Venus would
still
be 47
is
east of the Sun.
47 it
would shine out
before any but the very brightest stars makes star.
sunset,
above the western horizon (halfway to
zenith). In the darkening twilight
the evening
At
its
brilliantly
appearance. It
is
THE SEVENTH PLANET
9
But three hours after sunset, the turning Earth has caught up it and it sets. Venus can never be seen, in the ordinary man-
with
ner of speaking, higher than halfway to zenith, or for longer than three hours after sunset. (Venus
when
occasion
the Sun
and only
to look
is
is
bright enough to be seen on
in the sky,
just barely. Let's
but only
if
you know where
not count that, nor
let us
count
observation by specialized instruments in broad daylight.) If
Venus,
tion,
as evening star,
is
anywhere but
at
maximum
elonga-
lower in the sky and can be seen for correspondingly
it is
shorter times after sunset.
When Venus is at maximum Sun; that
is,
to
its
elongation on the other side of the
west, the situation
hours before the Sun and
isn't
morning, however, and Venus
is
different. It sets three
seen in the evening at rises in
all.
Comes
the east three hours before
the Sun and reaches a point halfway to zenith by sunrise. Before sunrise
it is
shining brightly in the
dawn
morning
as the glorious
star.
It
took the ancients some time to see that the evening star
and the morning tually
star
were not two different objects.
borne in on observers that when the evening
It
star
was evenwas
ent in the sky, the morning star was absent, and vice versa. also
noted that when the evening
there was a wait of several days
star
moved
The
They
close to the Sun,
and then the morning
peared close to the other side of the Sun.
pres-
star ap-
two were seen to be
a single planet.
Next,
let's
situation
much
of
is
it
frustrating.
Then, gets to
it
as
When Venus
can be seen as possible,
the Sun and
only see
consider the phases of Venus. In a way, the phase
is
therefore
is
it is
well
full so
on the other
some 150,000,000 miles away.
that as side of
We
can
as a comparatively tiny object. it
approaches close to us on this side of the Sun and it is at maximum, we see Venus gets, the less of its visible Venus is covered by a perpetual cloud
be at only one-sixth the distance
The
mostly the dark
side.
surface
(Of course,
is
near the
sunlit.
closer
10
THE SOLAR SYSTEM AND BACK
layer so that
we
can't see anything anyway, but
of the thing that
As
is
it's
the principle
so exasperating.)
a result, in considering the brightness of Venus,
take into account two opposed effects. As us, it gets
dimmer because it
turns out that
fat crescent stage,
At that moment
junction.
We
Venus
maximum
between
have to
is
times as bright as Sirius, the brightest
is
The mere
it
is
in a
is
is,
in fact, the third
by the Sun and the
said to
be bright enough
dim shadow.
fact that
an important
some com-
when
—4.3, or just about ten
star. It
and, on a clear, moonless night
to cast a very
from
and brighter
elongation and inferior con-
magnitude
its
we must
farther
strike
brightest
brightest object in the heavens, surpassed only
Moon,
moves
of increasing distance,
because of increasing sunlit area.
promise and
it
Venus's phases
exist at all,
however, played
role in scientific history.
In 1543, Copernicus advanced the heliocentric theory of the solar system, suggesting that the planets, including the Earth, re-
volved about the Sun, instead of having
all
the planets, including
the Sun, revolve about the Earth.
took nearly a century for the Copernican theory to be ac-
It
cepted by astronomers generally. Usually, this
is
looked upon as
a measure of the bigotry and general nastiness of Big Science, but it
wasn't.
ient
way
The Copernican
mathematics was a bit system.
mean
To
it
theory was a somewhat more conven-
of calculating planetary positions into the future.
Still,
because
easier
it
The
than in the case of the Ptolemaic
was a mathematical shortcut, did that
also portrayed the solar system as
it
was?
consider Copernicanism physically true as well as mathe-
some observational evidence was needed, not show any parallax, as have done if the Copernican theory were correct, it
matically convenient,
and none
existed! In fact, since stars did
they ought to
could be argued that there was at least one piece of observation that was against Copernicus. (Copernicus maintained that there
were indeed parallaxes but they were too small to be measured.
THE SEVENTH PLANET
He
was
right,
11
but the observational evidence for that was not
col-
lected until three centuries after his death.)
Without
why
observational evidence,
should anyone believe
that the firm Earth beneath his feet was flying about the
without his being aware of century,
I
it?
Had
I
been
Sun
living in the sixteenth
wouldn't have believed any such cock-and-bull
story,
either.
But then came Galileo and found that Jupiter had four
he
his telescope. In January, 1610,
satellites circling
of blow to the Ptolemaic view since
it
it.
This was a kind
showed that there were
at
least four objects in the
heavens that were manifestly circling some
body other than Earth.
It
was not
be maintained that Jupiter and
tem that
circled the Earth.
would be
affected.
It
its
No
was Venus that was the
fatal,
though, for
it
could easily
four satellites were a single sys-
other point of Ptolemaic theory
crucial planet.
The
only
way the
Ptolemaic theory could have Venus traveling about the Earth
and
still
move
in the heavens as
it
did (using the orbital mecha-
nisms they insisted on using) was to arrange matters whereby
Venus
oscillated
back and forth from one side of the Sun to the
other, while always remaining
mean
between the Sun and the Earth.
Venus would always be at half-Venus or less; it would always be some sort of crescent, thick or thin. On the other hand, by Copernican theory, Venus would travel completely around the Sun, and therefore, as described earlier in the article, would display all the phases from new to full, in just the manner our own Moon does. In 1543, there were no telescopes and no one could tell whether Venus showed phases at all, let alone what kind. So when Copernican theory was born, the phases of Venus could not serve as
This would
that
observational evidence.
But then, covered the
in September, 1610, eight satellites of Jupiter,
Venus and found
it
more than
months
after
he had
Galileo turned his telescope half-Venus.
dis-
on
THE SOLAR SYSTEM AND BACK
12
Galileo was enough of a scientist not to want to rush into print half-cocked. It was important that he follow orbit
and make sure that
its
On
according to Copernican predictions.
enough of
a self-centered
human
for the discovery simply because
He little
Venus
all
through
its
phases followed in order, precisely the other hand, he was
being not to want to lose credit
he was being cautious.
therefore published the following Latin sentence in
the
newsletter he was putting out concerning his investigations:
Haec immatura a me iam frustra leguntur, o. y. This means "In vain were these things gathered by me today, prematurely." This is a sort of dim hint that he was onto something he was not yet ready to disclose, but the sentence was an
anagram and when the ture of his discovery.
the anagram
letters
(The
come out
were rearranged
"o. y." at the
it
gave the true na-
end was needed to make
correctly.)
Rearranged, the sentence went:
Cynthiae figuras aemulatur
mater amorum. This means "The mother of love imitates the appearance of Cynthia." This scarcely seems clearer but figurative in
an age
in
which
Galileo
intellectual society
knew
was being their
Greek
myths.
To
begin with, Apollo and Artemis were born on Mt. Cyn-
thus on the island of Delos, according to the myths, and were therefore sometimes called Cynthius
and Cynthia
respectively.
Artemis was commonly considered to be a representation of the
Moon. Consequently, Cynthia As
for the
"mother of
love,"
is
a classical epithet for the
who
Moon.
could that be but Aphrodite
(Venus), the mother of Eros ("love"). So, in effect,
what Galileo was saying was: "Venus
phases like those of the Moon," which
is
displays
what the Copernican
theory required and the Ptolemaic theory forbade.
That
settled Ptolemy's
hash and put Copernicus
in business,
except for the inevitable die-hards (mostly, but not entirely, non-
astronomers).
THE SEVENTH PLANET Although Venus can be seen only
13
for limited periods
after
sunset or before sunrise, those limited periods are long enough to
allow
Venus
If a
to be a prominent object indeed.
planet
Greek
considered, in
is
moves against the background of
be any body that
fashion, to
stars,
then
have no doubt that
I
Moon was the first planet to be discovered, for observation the Moon on any two successive nights is enough to show that
the of it
has moved against the stars. The Sun would have been the second
became
planet discovered. It soon
clear that the starry pattern of the heavens shifts
from
night to night, and that would have been blamed on the ap-
parent motion of the Sun against the it
Such motion causes
stars.
to blot out a gradually shifting half of the sky.
But then the
Venus
less
notable planets were detected, and of these
headed the
surely
It is
list.
by
particularly brilliant in the dying twilight
beginnings of presenting
The
dawn when the Venus with
and with respect Call
Venus the up
to
in the glimmering
other stars are washing out and
respect to the
to the other stars,
it is
Sun
is
soon obvious,
only slightly
less
obvious.
third planet, then, historically speaking.
Mars, Jupiter, and Saturn are heights,
and
it is
competition.
little
shift of
and
far the brightest;
and including
all visible in
zenith.
Of
the night sky at
these, Jupiter
is,
all
on the
average, the brightest, over twice as bright as the star Sirius.
However,
for a short
as Jupiter and, it is
on
time every other year, Mars
rare occasions, even a bit brighter.
the background of the stars some does. It seems to
as bright
more eye-attracting than Furthermore, Mars moves against
of a distinctly reddish color that
the ordinary white of Jupiter.
is
What's more,
six
is
times as rapidly as Jupiter
me, then, that Mars must have been the fourth
planet to be discovered.
Saturn quickly.
is
dimmer than
So Jupiter
order of discovery.
is
the
Jupiter
fifth
and moves
less
than half as
planet and Saturn the sixth in the
THE SOLAR SYSTEM AND BACK
14
That leaves Mercury which, I maintain, was surely the seventh and last planet to be discovered by naked eye. Why? Well, it is the nearest planet to the Sun, nearer even than Venus, which
means that it shows all the more pronounced fashion. Because
move
it is
as far
maximum
about 27
is
That means
zenith.
Sun than Venus
closer to the
is,
it
doesn't ever
from the Sun (from our Earth-based view)
does. Mercury's
conditions
Venus, but in
orbital peculiarities of
it
,
as
Venus
elongation under the most favorable
or less than one-third of the
can only be seen at most for
way
to the
than two
less
hours after sunset or before sunrise. In
there
fact,
is
another
is
least elliptical while Mercury's, of
those planets visible to the naked eye,
The Sun
is
which means
The more
the planetary orbits are
difficulty. All
but Venus's orbit
ellipses,
most
is
elliptical.
always at one focus of the planetary orbital it is
ellipse,
nearer to one side of the orbit than the other.
eccentric the ellipse
and the
less nearly a circle,
the
(and therefore the Sun) to one side than the
closer the focus
other.
In the case of Venus, the eccentricity for is
an explanation of
"eccentricity.")
is
0.0068. (See Chapter 8
This means that the Sun
66,750,000 miles from one side of the orbit and 67,650,000 miles
from the other
Venus
gets
cedes from
side.
to the it
These distances are, respectively, the closest Sun ("perihelion") and the farthest it re-
The difference is only 900,000 miles. maximum elongation, it may happen to
("aphelion").
When Venus
is
at
its
be at perihelion or at aphelion or anywhere if
it
is
at perihelion
smaller
maximum
ference
is
it
is
closer to the
elongation than
so small, however, that
if it it
in between. Naturally,
Sun and has
a slightly
were at aphelion.
The
dif-
can be neglected for ordinary
purposes.
Not
so in Mercury's case. Its orbital eccentricity
Mercury
When
it
is
closest to the
is
farthest,
it
Sun is
again as far as perihelion.
it is
is
0.21.
When
at a distance of 28,500,000 miles.
43,500,000. Aphelion distance
is
half
THE SEVENTH PLANET That means there
mum
elongation
is
15
a tremendous difference between a maxi-
when Mercury happens
to be at aphelion
and
one when above, all
is
it happens to be at perihelion. The figure of 27 given , an elongation at aphelion and represents the greatest of
maximum elongations. maximum elongation
possible
At
perihelion, the
ten minutes after sunset or
rises
under 18
just
is
Mercury hugs the horizon and
these times,
.
At
an hour and
sets just
an hour and ten minutes before
sunrise.
And mind and
you, these viewing times of
hour at some times
1
moment
2 hours at other times are only at the
of greatest
elongation, say two or three nights in every 3-month period.
other times, Mercury
all
Sun and
closer to the
is
is
At
viewable for
smaller periods.
We can summarize by saying that Mercury when
it
is
is
hardly ever visible
(Astronomers use special instruments to
truly dark.
no help to a naked-eye observer like an ancient Greek or a modern me.) What's more, Mercury has other disadvantages as a viewable
observe
object.
it
in the daylight
To be
but that
is
sure, it is closer to the
of
Sun and
is
more
brightly
square mile for square mile, than are other planets; but smaller than
Venus and
gets less total light.
Where Venus
it
lit,
is
has a
diameter of 7,550 miles (almost that of Earth), Mercury's diameter is only 3,030 miles. Mercury is, in fact, the smallest of the planets.
Then,
too,
the light that
Venus has falls
upon
atmosphere and must the
Moon
like
the
does.
Moon,
There reflects
it.
only about
both at their brightest, Mercury
Add
Venus all
of
from
its
bare rock surface as
every reason to suppose that Mercury,
Finally, in the crescent stage, at
us than
%
Mercury, on the other hand, has no
reflect light is
some
a cloud layer that reflects
is
%4
of the light
it
receives.
which Mercury and Venus are considerably farther away from
is.
these things together—that
Mercury
is
smaller than
THE SOLAR SYSTEM AND BACK
l6
Venus,
and
farther away,
is
prising that
Mercury
is
light— and
reflects less
much
dimmer
the
not
sur-
of the two. Mercury, at
very brightest, has a magnitude of —1.2 and
its
is
it
is
y17
only
as
bright as Venus. It is
not the least bright of the planets. Saturn has a
when Mercury
brightness of —0.4, so that
at
its
best
maximum twice
it is
However, Saturn can be viewed in the calm
as bright as Saturn.
darkness of the middle of the night
the heavens and where
when
be seen only near the horizon
in
it
may well be high in among the twenty
out as
will stand
it
brightest stars or starlike objects. Mercury,
Sun
is
dawn
on the other hand,
or twilight,
will
amid haze and
glare.
There
is
no question
in
my
mind, therefore, that Mercury was
the seventh planet to be discovered.
people today (when the horizon the sky
much
There
is
is
much
and
dirtier it
was
have never seen Mercury.
even a story that Copernicus himself never saw Mer-
though
There
is
many
suspect, in fact, that
generally
hazier with the glare of artificial light than
in centuries past)
cury,
I
I
can hardly bring myself to believe that.
a curiosity here that
some Gentle Reader points
it
I
would
like to
point out before
my
discussion of the
out to me. In
seven metals of the ancients later in this book (see Chapter 12) I
point out that the metal mercury was probably the seventh
and
last
metal to be discovered by the ancients.
And
here
I
say
that the planet Mercury was the seventh and last planet to be discovered, so that
Furthermore, for the planet
I
it is
entitle this chapter
known
Mercury.
metal was named know more than
"The Seventh
Is it entirely a
named
coincidence that the seventh
Or
for the seventh planet? is
Planet."
that the metal mercury was
generally thought,
did the alchemists
and did they know the
order of discovery of metals and planets and arrange the names to correspond? I
know
there
lieve in the
is
a strong tendency
on the part of mystics to be-
"wisdom of the ancients" but
I
don't think they were
THE SEVENTH PLANET The correspondence between
that wise.
all
a coincidence, in
my
are such things as pure coincidence,
and
seventh planet
How
is
long does
Sun? At
first
seventh metal and
opinion. After this
take for Mercury and
it
blush,
17
is
Venus
The
planet
then have started at the point between ourselves and the Sun,
gone
come back
around, and
all
and the Sun. It takes Mercury 116 days is
around the
to go
might seem that one need only count the
it
days between one inferior conjunction and the next. will
there
all,
an example.
to the point
do
to
this
between ourselves
and Venus 584
days. This
the "synodic period of revolution." It
however, a
is,
strictly
Earth-related period. After
the
all,
moving around the Sun, too. If Mercury starts at a certain point directly between ourselves and the Sun, then moves around the Sun back to the same point (recognized by its position relative to the stars), it will turn out that the Earth is no longer where it was. It has gone its own way and, since Mercury left, has Earth
is
completed about one-quarter of
its
own
revolution.
Mercury must continue turning until it catches up with Earth and gets in between it and the Sun again. Mercury, which is so
moves
close to the Sun,
faster
than any other planet relative to
(30 miles per second, as compared with our
second).
we
calculate
in
in
88 days. This
usual period
The
we
situation
long
it
takes
Mercury
to return to the orig-
own motion
it
turns out that Mercury revolves about the
is
the "sidereal period of revolution" and
in
Sun
is
the
Venus. In the
first
speak of as the "length of Mercury's year." is
more extreme
in the case of
place,
Venus
make
a longer sweep to go about
is
us, there-
about a month.
how
inal spot relative to the stars, regardless of our
the interim, then
it
18.5 miles per
does not take very long to catch up with
and does so
fore, If
It
own
farther
from the Sun than Mercury it.
It
is
and must
moves more slowly than
Mercury does (only 22 miles per second) and takes a much longer time to
make the
greater sweep.
THE SOLAR SYSTEM AND BACK
l8
By
the time
it
returns to
its
original point relative to the stars,
Earth has had a long time to move on
its
orbit
and has gone
three-fifths of a revolution.
Venus does not move much more quickly than the Earth does it can gain on us only slowly. It must make a second full turn about the Sun and then a half-turn before it catches up. If we count only the time it takes Venus to go around the Sun with reference to the stars and disregard the moving Earth, then the sidereal period of revolution of Venus turns out to be 225 days. and
Which
brings
me
two planets about
finally to
the matter of the rotation of these
their axis, old view
and new view, and we
continue with this subject in the next chapter.
will
THE DANCE OF THE SUN
2
Occasionally
I receive
one that was
rather depressing letters. Once, I received
and
several pages long
but the beginning was clear enough. of
It
largely incomprehensible,
objected strongly to a book
mine on astronomy.
The
writer claimed that
tant matter,
my
showed
I
had neglected one supremely impor-
and the implication was strong that
incompetence.
He
complained that
I
this
neglect
had spent much
time describing the universe and trying to give a picture of then
totality,
left
out the key point.
up?" he demanded. it
from
The
"Why
what keeps
proper answer would have been: "Fall where?" but that just gotten
him angry without
I tried
to read his explanation of
falling,
an explanation
I
this
mind
is
just
after
enlightening him. After
what kept the universe from
couldn't understand,
thing was not to answer at
zles
holds the universe
didn't you try to figure out
falling?"
would have
But
"What
its
I
decided the wisest
all.
one example of the type of question that puz-
mind and which no explanation seems
to answer
properly.
There are always people who
aren't satisfied that the law of
THE SOLAR SYSTEM AND BACK
20
means that
"But what
And
Moon
move
in a
vacuum.
are the exhaust gases pushing against?" they
demand.
action and reaction
there are
a rocket can
some people who
can be rotating
if it
will never
always see the same side," they say, "then Naturally, there
is
once and for
and
all. I
it
an awful temptation
case of compulsive explainitis, as analysis so clear
be
the
satisfied that
always faces the same side to us. "If
(if
have)
I
we
can't be turning/'
one has an advanced
some
to try to find
so irrefutable as to explain the
whole thing
have, for instance, tackled the problem of the
Moon's hidden side on a number of previous occasions and now I'm going to do it yet again in a new way. This time, though, I have an ulterior motive. I want to do it so I can continue talking about Venus and Mercury, a subject I brought up in the preceding chapter.
To
begin with, each planet has two chief movements: (1)
turns, or rotates,
about
the Sun. First,
let's
its axis,
and
(
2
)
it
turns, or revolves,
it
about
consider the matter of rotation about the
axis.
By
convention, the axis (an imaginary line) defines north and
The
south.
axis intersects the surface of the
Earth at the North
Pole at one end and at the South Pole at the other.
Suppose, now,
we imagine
ourselves high in space, exactly over
the Earth's North Pole. Looking
down upon
the Earth, the North
Pole would appear exactly at the center of the planetary
(Of
Sun— a in the
little
more than
winter— and the
half in rest
we
circle.
would be lit up by the the summer, a little less than half
course, only half the circle
would be
see
in darkness,
but
we'll ignore
that as an unimportant detail.)
From our vantage see the
about
point directly above the North Pole,
whole planet turning about
its
it
we would
exactly as a wheel turns
hub.
But which way does the planet turn? There are two possible ways, and these can be most easily described by reference to the face of a clock. We all know the way in which the hands of a clock turn. Well, the normal progression of the hands from
1
to
THE DANCE OF THE SUN 2 to 3 tion,
As
on the
from it
face of the dial
is
"clockwise."
21
The
opposite direc-
3 to 2 to 1, is "counterclockwise."
happens, the Earth, as viewed from above the North Pole,
turns counterclockwise. This counterclockwise rotation, from a
view on the Earth's surface, means that our planet turns from west to
east.
You can
see this for yourself,
in your house (or,
if
you have a mounted globe
if
you are very enthusiastic, you can find one
in
the local school or library). Turn the globe from west to east, and look
down upon
see that
it,
as
it
turns,
from above
its
North
You
Pole.
will
turning counterclockwise.
it is
However, if you continue to rotate the globe from west to east and bend down so that you can see what is happening from a view over the South Pole, then you will find the Earth, from that vantage point,
is
turning clockwise.
of turning, then, you
must
To
give
meaning to the
specify the point of view,
conventional always to suppose that the view
is
direction
and
it
is
from above the
North Pole. This orientation can be applied to the solar system generally, because
it
happens that
all
the major planets are located close to
the plane of the Sun's equator, and
all
the axes of
all
the planets,
with the exception of Uranus, happen to be within 25
of the
perpendicular to that plane.
we imagine ourselves reasonably high above the North Pole of the Earth, we are also high above the general plane of the solar system. If we then move over the Sun, we would This means that
if
one end of its axis points more or less toward Sun moves counterclockwise about it. We would
find that
that the
same thing
to
be true
if
we moved
us,
and
find the
over Jupiter, Saturn, Mars, and
so on.
This represents a fine display of orderliness, clockwiseness, but
take
up
I
all
this counter-
warn you there are exceptions, which
I will
in the next chapter.
But what
if
mankind ever engages
colonizing the planets of another Sun?
north and which south?
To
refer
in interstellar travel
Which
and
pole should he
is
call
back to the plane of our own
THE SOLAR SYSTEM AND BACK
22
system would be inconvenient and, at times, useless.
solar
dict that the star itself will axis its
about which
it is
But
let's
get back to the Earth
the only motion
tion, it
A
and the Sun. The Earth
it
has.
person standing on the surface of the Earth will not
still.
its
be interpreted
As the Earth
on
its
rotat-
its
rota-
will
feel
the
seem, to himself, to be
on which he stands
is
con-
orientation with respect to the Sun, but that
as caused
rotates
by the
fact that the
from west to
surface that the
to west. Because the real
clockwise,
He
Naturally, the point
stantly changing
server
is
that this
We will suppose that, except for
planet to be rotating, however.
will
moment
motionless with respect to the Sun.
is
standing
satisfac-
planetary system generally.
its
ing counterclockwise and we'll suppose for a is
its
rotating counterclockwise will be defined as
north pole. That will almost certainly define north in
tory fashion for
pre-
I
be used as reference. That end of
east, it will
Sun moves
Sun
moving.
is
appear to an ob-
across the sky
motion of the Earth's surface
the apparent motion of the Sun
is
from is
east
counter-
clockwise (see
Figure 2).
We can measure the rate of turn as so many degrees per unit of time; say, so
many
one complete
turn.
degrees (°) per day where there are 360
in
Since clockwise and counterclockwise are rotations in opposite directions,
let's
arbitrarily
and counterclockwise turns For instance,
if
give clockwise turns a
positive
sign
a negative sign.
a planet turns counterclockwise on
its
axis ex-
one day, we would say it turned — 360 ° per day. To a person on its surface the Sun would seem to make a complete clockwise turn about the sky in one day. We could then say that the apparent motion of the Sun, resulting from the planet's rota-
actly
once
tion,
is
We
in
+360 per
day.
don't, however,
have to pin ourselves down to any one
planet moving at any one rate.
We
can talk about an arbitrary
planet which happens to be turning on
its axis
at a rate of
— x°
THE DANCE OF THE SUN From
per day.
through
Mind motion
its
its
that of turning
is
on
second important motion.
its axis.
It revolves
Every planet, however, has a
about the Sun as well.
we imagine
If
Pole, self,
Sun would seem to be moving +x° per day. for a planet whose only important
surface, the
sky at the rate of
you, though, this is
23
ourselves, now, to be high above the Sun's North and observe the planets revolving about its giant, luminous
we would
terclockwise.
see that every major planet revolves about
There are no exceptions.
these counterclockwise rotations and
(All
this
revolutions,
Figure 2 Rotation APPARENT CLOCKWISE MOTION OF THE SUN
STATIONARY SUN
WEST
EAST
EARTH
it
coun-
regularity— all
with so few
THE SOLAR SYSTEM AND BACK
24
ones—has to be explained. them that all modern theories
from attempts to
clockwise
It is
plain
of the origin of the solar
ex-
system have arisen.) Let's consider, then, a planet revolving about the
terclockwise fashion and, to this
is
Sun
let's
in coun-
pretend that
we considered that was rotating but not revolving; now we are going to a planet that is revolving but not rotating. To show that is not rotating as it revolves about the Sun, we will make
consider a planet little
same
things simple,
the only important motion
a planet
the
make
it
has. Earlier,
arrowhead, representing an observer, face always in the
direction.
As the planet from Figure
revolves about the
3 that the
Sun seems
Sun to
in this way,
move
you can see
in the sky,
from the
viewpoint of an observer at a fixed point on the planet's surface.
What's more,
as the planet revolves in counterclockwise fashion,
the apparent motion of the Sun that results
is
also counterclock-
wise.
Then,
too, the apparent
of planetary revolution, real
motion of the Sun
motion of the planet about the Sun.
in the sky, as a result
terms of degrees as the
just as great in
is
When
the planet makes
one complete turn (360 ) about the Sun, the Sun appears to make one complete turn about the sky. Suppose a planet revolves about the Sun, counterclockwise,
in
moving
at
exactly 36 days. In a rate of
— io°
for carrying
it,
1
day,
per day.
it
travels Ysq of
360
The apparent motion
,
so
it is
of the
Sun
also counterclockwise, across the sky at
is
there-
— io°
per
day.
Again, a rate of
let us
— y°
be general.
— y°
across the sky at If,
If
the planet moves about the Sun at
per day, then the Sun, in response, appears to
move
per day.
then, a planet both rotates
and
revolves (as
is
always true),
the Sun's apparent motion across the sky is +x° per day due to the rotation and — y° per day due to the revolution. The total
motion
is
Let's see
(+x°)
how
+
this
(— y°)
or,
more
briefly,
(x
—
y)° per day.
works out in the case of the Earth.
The
ap-
Figure
SUN'S APPARENT COUNTERCLOCKWISE MOTION ACROSS THE SKY
Revolution
O
o
o
3
*
\
O
EARTH'S COUNTERCLOCKWISE REVOLUTION ABOUT
THE SUN
THE SOLAR SYSTEM AND BACK
26
parent motion of the Sun in Earth's sky, due to Earth's rotation
and
revolution,
is
such that, on the average,
x
—
y
We tion
can calculate
its
y,
can
makes one comsay,
then,
that
the component of the Sun's apparent mo-
Sun
turn around the
one day
it
per day, in the case of the Earth.
360
due to Earth's revolution,
pletes in
=
We
sky in one day.
plete circle of the
it
enough.
easily
about 365.26 days so that
in just
moves %65.26 oi 360
.
The Earth com-
This comes to 0.9856
per
day.
= — 0.9856 per day, we can say then, that in the case of Earth, x — 0.9856 = 360 If we then solve for x, we find that x = 360.9856 If
y
.
.
This means that the Sun's apparent motion about the to Earth's rotation only,
turn of 360
in
sky, due more than one complete
a little bit
is
one day. Instead,
moves
it
just
about 361 °, with
that extra degree canceled by the part of the motion that
is
due to
the Earth's revolution about the Sun.
To make one would take a
turn of exactly 360
trifle less
,
due
than one day.
to Earth's rotation only,
It takes
24 hours to turn
361 °, but only 23 hours 56 minutes to turn exactly 360
We can see that this
is
so
.
by studying the motion of the
stars.
Every object in the heavens beyond the atmosphere has an apparent clockwise motion across the sky in response to the Earth's counterclockwise rotation.
The
stars,
The
stars do, as well as
the Sun.
however, have no progressive apparent motion across
the sky in response to Earth's revolution about the Sun. In the case of the Sun, the Earth is
moves about
it
bodily so that the
Sun
constantly being viewed from a changing vantage point. In the
process of this bodily motion about the Sun, though, the Earth's position with respect to the very distant stars can scarcely be said to change.
The
stars, therefore,
do not
alter their
tions at all (except for tiny elliptical motions
it
apparent posi-
takes a first-grade
telescope to detect).
For
stars then,
the apparent motion due to rotation
day, which in the case of the Earth
is 361 °
is
+x° per
per day, while the ap-
THEDANCEOFTHESUN parent motion due to revolution stars
The total motion of the make a complete turn in
per day, and they therefore 36 ) in %6i of a day, or 23 hours 56 minutes.
°
361
is
zero.
is
27
the heavens (360
And
the stars are observed, the time lapse between successive
if
crossings of the zenith meridian does indeed turn out to
hours 56 minutes. This period of time
is
be 23
therefore the "sidereal
day" (from a Latin word meaning "stars") while 24 hours
sidereal
move
The
day."
"solar
the
is
four-minute-per-day discrepancy between
day and the
day
solar
the
what makes the Sun appear
is
to
against the background of the stars.
And what happens period of
—
that case x
the period of a planet's rotation and the
if
revolution
its
y and x
—
(both counterclockwise) are equal? In y
=
o° per day.
Thus, when a planet rotates and revolves in the same period of time, the
Sun does not appear
move
to
in the sky. It remains in
the same spot constantly.
As seen from the Sun, the
planet, as
it
revolves,
would always
present the same face to the luminary. In this way, the
Sun
would always shine on the same face from the same angle, which is
equivalent to saying that the
Sun does not appear
to
move
in
the sky.
The Moon
Moon
respect to
that the
it
that a
same
Moon
is
Sun does
face to us at
might seem that
it
we
a
means that the periods
of ro-
It
Moon.
tremendous coincidence that the
periods of rotation and revolution should be equal, but, as pens, this
upon
is
a small
not
so.
The
(The
times.
mean
identical for the is
all
play the same role with
to a planet.) This does not
not rotating.
and revolution are
tation It
presents the
revolves about the Earth so that
it
gravitational influence of a large
body revolving about
itself is
hap-
body
such as to force the
period of rotation and revolution into equality.
The
greater the disparity in the size of the
closer together they are, the
tion
more
two bodies and the
rapidly are the periods of rota-
and revolution of the smaller body brought into
equality.
THE SOLAR SYSTEM AND BACK
28
The Earth
Moon, and until Sun had succeeded
has succeeded in doing this to the
very recently,
it
was taken
for granted that the
in doing so to Mercury.
Not only did gravitational theory make it seem reasonable that Mercury presented only one side to the Sun, but also observational evidence seemed to back that view. If one side of Mercury always faces the Sun as it revolves, then only that one side
ever
is
lit
up and only that one
is
If
viewed over and over again at some particular point in
relative to the
Earth then that
the same angle.
lit-up side
Any markings on
be Mercury
side can ever
seen by an astronomer peering through a telescope.
its
orbit
ought to be seen from
that side would be the
same
at
each viewing. Conversely,
Mercury
is
the visible markings are the same every time
if
viewed at some particular point in
its
orbit,
then the
planet would be proved to face one side always to the Sun. It
would then follow that the period of Mercury's rotation about its axis would be the same as the period of its revolution about the Sun.
The to the
trouble
and
that Mercury's distance, smallness,
is
Sun make
its
markings very
closeness
difficult to observe.
Nevertheless, in the 1880's, the Italian astronomer Giovanni
Virginio Schiaparelli tackled the problem. (or thought
so often that in the
time
had
to
he
it
of revolution tion
By
he had seen) the same markings felt it safe to say
took is
it
he had seen same position
that Mercury rotated
on
its
axis
to revolve about the Sun. Mercury's period
88 days (well, 87.97 days) and
be 88 days
This was accepted.
1890,
in the
its
period of rota-
as well.
It fit theory,
and
Schiaparelli
was known to
be an excellent observer. For three-quarters of a century, the
ment about Mercury's
facing one side only to the
state-
Sun was
re-
peated in every general astronomy book written.
But then, in 1965, radar waves were bounced off the surface of Mercury and the echoes were caught in receivers on Earth. From
THEDANCEOFTHESUN the nature of the echoes
it
is
waves
is
rotating or not and,
reflecting the radar
possible to
29
whether the body
tell
how
rotating,
if
fast.
It
turned out that Mercury
is
not rotating about
days but in 58.6 days, and this meant that
it is
its axis
in 88
not facing one side
always to the Sun. Mercury's Sun side and night side, so dearly
beloved by science-fiction writers, vanished into thin If this is so,
Well, If
how came
then
Schiaparelli to
make
air.
his mistake?
let's see.
Mercury
rotates
on
its
axis in 58.6 days
and does
so in coun-
terclockwise fashion, then x (the apparent motion of the Sun, due to planetary rotation)
is
equal to +6.14
per day.
The
period of
revolution remains 88 days, however, also counterclockwise, so
that y (the apparent motion of the Sun, due to planetary revolution) is — 4.09 ° per day.
The
total
apparent motion of the Sun as seen from Mercury's
surface, then,
is
—
6.14
4.09 or 2.05
per day. For the Sun to
make
one complete turn (360 ) at this rate would take 176 days. To put it another way, from Mercurian noon to Mercurian noon is 176 Earth days.
Do is
you notice a coincidence?
It
turns out that 176 Earth days
exactly twice the period of Mercury's 88-day revolution. Sup-
pose, then, that at particular place
some
on Mercury's surface
Exactly two revolutions the Sun again.
particular point in Mercury's orbit
And
later,
exactly
that
is
same place
two revolutions
the in-between revolutions, that place
from the Sun and
it is
planet that gets the
directly
one
under the Sun.
is
directly
under
later, still again.
In
pointed directly away
is
the place on the exact opposite side of the
full blast
of the Sun.
In this case, particular markings would show up on Mercury's lighted
side at particular points
in
its
orbit
in
every second
revolution. Schiaparelli, observing
Mercury, had a devil of a time making
out markings, and observed most earnestly
when Mercury was
at
aphelion and furthest from the Sun. Clouds, haze, heat quiver-
THE SOLAR SYSTEM AND BACK
30
must have ruined innumerable potential
ings
number
of occasions, though,
markings, he imagined
them
he expected them to be. were missing, he
He
when he
to be the same, since for
poor
felt justified in attributing it to
assumed, very naturally, that
so often, they were there to
astronomers never
make
a
certain
one
thing,
on occasion, the familiar markings
If
meant Mercury faced one
On
sightings.
make out
did
if
he saw
visibility.
particular markings
be seen every time, and that that
side to the
Sun
all
the time.
(I'll
bet
that mistake again.)
This peculiar form of rotation in which the planet presents front to the Sun, then
first its
back,
its
is
astronomers had ever predicted in advance.
not something that
Now
they are busily
engaged in trying to find out what conditions are required to have such a situation
All
I
have
result.
said, so far,
assumes that a planet's rate of rotation
and revolution are constant. This planetary rotation about
its
axis.
invariably true in the case of
is
It
is
not necessarily true for
planetary revolution about the Sun.
For a planet's rate of revolution about the Sun to be constant, its
orbit
circle, its
must be a perfect revolution
Mercury's orbit of
its orbit,
Mercury
at the opposite
is
isn't
end
is
circle. If it is
merely almost a perfect
merely almost constant. even almost a perfect
circle.
At one end
only 28,500,000 miles from the Sun, while
it is
43,500,000 miles from
it.
When
nearest
the Sun, Mercury moves at a speed of 35 miles per second relative to the Sun.
When
farthest away,
it
moves only
at a speed of 23
miles per second. If
Mercury's period of rotation and revolution were exactly equal,
then the inconstancy of
from remaining
While at
its
in
its
one spot
orbital speed
would prevent the Sun
in the sky as seen
closest to the Sun,
from Mercury.
Mercury would be moving
so fast
that y (the Sun's apparent motion due to the planet's revolution) would be considerably greater than x (the Sun's apparent motion due to the planet's rotation). This means that x — y would be a
THE DANCE OF THE SUN negative quantity, and the
Sun would be
31
drifting west to east
(clockwise) across Mercury's sky.
By
the time Mercury was moving toward that part of
that was farthest from the Sun,
its
orbit
so slowly as
behind the rotational period. Then y would be smaller than
to fall x,
would be moving
it
—
and x
The Sun would
y would be a positive quantity.
drift
west to east (clockwise).
On
the whole, then, the Sun would slide
then
westward,
every 44 days, but maintaining If
first
eastward, then
changing
seem
to
But its
tip, if
mark out
all this is
any,
narrow
a
only
is
direction
average position unchanged.
its
Mercury's axis were somewhat tipped to the Sun
quantity of such
to
westward,
then
eastward,
(and the
not yet certain), the Sun would
ellipse in
Mercury's sky.
Mercury's period of rotation were equal
if
period of revolution, which
it isn't.
The Sun makes
a
com-
plete circuit of Mercury's sky thanks to the planet's nonequal
period of revolution. Imposed upon this
motion produced by the planet's
The
result
is
is
the back-and-forth
orbital eccentricity.
a remarkable dance of the
Sun
science-fiction writer has ever envisaged as far as
I
of a kind
no
know.
Suppose, for instance, you were on a spot on Mercury's surface
which happens
to
have the Sun directly overhead when
at
its
actually at
its
it is
closest.
You
will see the
farthest
from Mercury.
width of the Sun as hot.
Sun
As
it rises
as seen
rise in It
(which
it is
at
its
closest
it
and
the width of the Sun as In fact, the point at
its
is
in the
little
more than twice the
it
grows
largest. It
we
a half times
does slowly, for there are 88 days be-
see
it
By the time it is at zethen more than three times
larger. is
and ten times
on Mercury's surface
largest gets extra
quickly. It
then a
it is
from the Earth and four and
tween sunrise and sunset) nith,
is
the east, while
punishment,
as hot.
directly
for the
under the Sun
Sun does not pass
neighborhood of the zenith that the
ing eastward again. After a while
it
orbital
and sends the Sun movturns and goes westward
velocity overtakes the rotational velocity
7
THE SOLAR SYSTEM AND BACK
32
again, slipping past the zenith
horizon.
As
shrinks until
On
and continuing on
to the western
down through a long, long afternoon, its minimum size again as it sets.
it
slides
it
reaches
it
the directly opposite side of Mercury, the same thing hap-
pens. During one of Mercury's revolutions, one side gets
the next, the other side
does— in
Even more dramatic
it,
during
alternation.
are those places
on Mercury that are 90
removed from the places that get the Sun at zenith at
its largest.
There, the looping motion of the Sun that arises from the nonsteady orbital velocity of Mercury takes place it is
there that the
The Sun more
Sun
is
at
maximum
on the horizon, and
size.
more and
will rise in bloated fashion in the east, rise
slowly, then begin to slip
a second time and this time
it
back and
set.
After a while,
doesn't change
its
mind.
toward the zenith more and more quickly, shrinking as
At
zenith,
It
as
it
it is
down
minimum
to
moves
it
size.
sinks slowly in the west. it is
bloated to
By
the time
full size. It sets,
and
it
Then
it sets
approaches the
after a pause,
again as though to take a last look around and
make
it rises
sure all
is
again for good.
Mercury can thus be divided into four segments, which as to
goes.
sweeps past zenith without turning and begins to grow again
horizon,
well.
it rises
It
whether the Sun
is
high in the sky
when
it is
differ
relatively large
relatively small (Cool Zone). They are arranged Hot Zone, Cool Zone, Hot Zone, Cool Zone. It
(Hot Zone) or alternately:
should be remembered, though, that even the so-called Cool Zone is
super-torrid
What
I
by Earth standards. is the dance of the Sun as seen Hot Zone, then from the middle of
have described
the middle of the
Zone. Other places
differ in
from
the Cool
the exact place in the sky (how high
above the horizon) the large Sun goes through
Nor have we even
first
its
loop-the-loop.
yet exhausted the peculiarities of the rota-
tion/revolution combination. There
turn in the next chapter.
is still
Venus, to which
I will
BACKWARD, TURN BACKWARD
I rarely
take vacations because
occasionally
Some
do.
I
I
hate leaving
years back, the
spent a most successful three-day period in the
peak of the foliage season (and
at the very
New
the foliage turn in
my
typewriter, but
whole family (four of us)
if
White Mountains
you have never seen
England, you have never seen the world
in living color, that's all).
We came down railway (against
from
a trip
my will,
for
up Mount Washington on the cog
am no
I
dare-devil,
but
I
lost the vote
by the narrow margin of three to one) and found that idly getting dark.
My a
wife said, "If
whole I
cluster of
it
we
them
way we came, we
turn back the just a
it
was rap-
to find a motel. will find
couple of miles from here."
with the kind of man-of-the-family decisiveness that
replied,
made
That meant we had
clear there
was
to
be no appeal,
"I
never turn back!
We go
forward!"
And we forest,
did go forward.
We
went forward through
without people or other automobiles.
there were
no
street lights,
and
It
a
state
got pitch dark, for
for twenty-five miles
we went
for-
ward through a universe of blackness, while the children got progressively
more frightened and
I
got progressively more un-
THE SOLAR SYSTEM AND BACK
34
of
all,
we
drove through the most glorious stretch of foliage color in
all
the
easy (what
get a
if I
flat tire
world, and saw none of
On
the whole,
it
here and now!).
Worst
it.
was not one of
my more
intelligent decisions,
something the family nobly forbore saying more than a mere fifty-eight
times during the course of the epic drive.
cuse was a plaintively reiterated, "But
how
could
My
only ex-
we go
back-
ward?" There's something about going the "wrong way" or "backward" that upsets methodical, self-disciplined people like myself, upsets astronomers, too. constitutes frontward
For instance,
if
They have
and backward
you view the
Sun's north pole, then
it
and
distinct notions as to
in motion.
solar system
from high above the
turns out that of the nine major planets
from Mercury to Pluto, exactly nine revolve about the Sun a counterclockwise
it
what
manner
(as
I
explained
in
in
the preceding
chapter).
Therefore, counterclockwise motion
forward motion.
It is "direct
is
the right motion, the
motion." Clockwise motion
is
the
wrong motion, the backward motion. It is "retrograde motion" (from Latin, meaning "backward-stepping").
To be
sure, in order to
judge whether a planet
revolving
is
about the Sun counterclockwise or clockwise, from a position
above the Sun's north pole, the planet's orbit should, in the plane of the Sun's equator. This practice.
The
is
plane of the Earth's orbit
ideally,
be
not exactly so in actual is,
for instance, at
an
angle of 7 to the plane of the Sun's equator. The plane of the orbits of other planets is also tipped to one slight extent or another.
Fortunately, the orbital planes of the various planets are sufficiently close to
one another and to that of the Sun's equator to
enable us to speak of such a thing as a "general planetary orbital plane." This
is
very close to Earth's orbital plane, which
is
usually
referred to as the "ecliptic." I will speak of the "ecliptic" hence-
BACKWARD, TURN BACKWARD— forward as the plane along which the system (the Sun and
The
ecliptic
enough to
its
flat
nine major planets)
lies.
and the plane of the Sun's equator are
raise
no
Difficulties
would indeed
tipped through 180 is still
an equatorial
,
it shifts
orbit,
if
arise if
the plane of a planetary orbit
from an equatorial
but after the
clockwise, not counterclockwise.
the orbital
JL38JL84Q
plane were tipped considerably, however. see in Figure 4,
close
the matter of counterclockwise
difficulties in
and clockwise motion.
As you can
35
structure of the solar
shift,
orbit to
the revolution
Motion has become
is
what is
retrograde.
Figure 4 Orbital Tipping Equatorial orbit direct (counterclockwise)
Equatorial orbit
retrograde (clockwise)
l-EQUATORIAL
VIEW
NORTH POLE
If
the plane of the orbit
is
tipped through an angle of 90
,
it
orbit. Viewed from high above the Sun's north would be seen passing back and forth across the face of the Sun. Its orbit would be seen on edge and its revolu-
becomes a polar pole, the planet
tion If
would be neither counterclockwise nor clockwise. the plane of the orbit, after being flipped 180
motion, were flipped another 180
(360
into clockwise
altogether),
it
would
be equatorial again and back into counterclockwise once more.
THE SOLAR SYSTEM AND BACK
36
In the process, at
it
have gone through another ambiguous stage
will
270 There are a couple of .
"direct"
movement
and "retrograde" what is usually done tip
bad
its
An
for
were referred to only
there would be
were or
how
on astronomy, but it has to the ecliptic would be would be retrograde, and if
in popular writing
orbit that
is
tipped 87
and one that was tipped 93 °
direct this
points.
open to us. We can speak of on one side of the right-angle everything on the other side. This is
alternatives
for everything
as direct or retrograde,
no indication
relatively easy
of
it
how
close the
two
respectively,
cases actually
might be to switch an orbit from
that kind of direct to that kind of retrograde in the course of as-
tronomic evolution.
My own
recommendation would be to drop
and
direct
retro-
grade as far as possible and deal only with orbital tipping.
Any
from o° to 90 and from 270 to 360 would be anything from 90 to 270 would be retrograde.
and
tip
To is
no
be
sure, as far as planetary revolution
fear of confusion.
The
of Pluto, the orbit of which ecliptic,
which certainly
is
concerned, there
greatest orbital tipping is
isn't
in a plane that
enough
is
direct,
is
in the case
tipped 17
to confuse direct
to the
and
retro-
grade.
Nevertheless, there are tions to the solar system,
argument
more than and there
planets and orbital revolu-
will
appear some point to
my
yet.
The unanimity with which
the planets revolve in direct fashion
seems significant to astronomers, and
it
must be explained
theory describing the origin of the solar system.
The
in
any
current
theory has the solar system beginning with a vast cloud of dust
and
gas, rotating
about
that direct motion to
only do the planets rectly
about
Ideally,
by
its
own
all
all
its axis
in direct fashion,
and imparting
the parts that developed out of revolve directly, but the
Sun
it.
Not
rotates di-
axis, too.
this theory, there
should be no retrograde motion
BACKWARD, TURN BACKWARD— anywhere
in the solar system; yet there
motion must be explained,
is.
The
37
cases of retrograde
possible, without seriously affecting
if
the general description of the origin of the solar system.
For instance, comets all
amounts and
a
about the Sun in orbits tipped by
travel
number
of
them
therefore
move about the Sun
in retrograde fashion.
Explanation:
The comets may
very well exist, to begin with, in
a vast cloud spherically arranged about the Sun at a distance of a light-year or
1962).
They
two (see Chapter 8 of Fact and Fancy, Doubleday, represent the fringe of the original cloud of dust
gas, a fringe too rarefied to participate rapidly
enough
and
in the con-
densation of the inner portions and in the centrifugal force that spread the originally spherical cloud into a
quently
when some comets
(possibly
by the
flat
sheet.
Conse-
gravitational influ-
ences of other stars) are sent in toward the solar system proper
from out the vast cometary sphere, they can come in from any direction
and may be retrograde
as easily as direct.
Next come the asteroids. A number of them have highly tipped though actual retrograde motion is not to be found
orbital planes
among them. Explanation:
The
asteroids
may have
originated through an
explosion of a small planet once circling in the region between
Mars and
Jupiter.
The
planet was undoubtedly revolving directly,
but the explosion superimposed a second original
so that
effect
upon
movement. Portions were sent hurling in
some
of the resulting asteroids
And what about
move
that of the
all
directions,
in fairly tilted orbits.
the satellites?
Presumably, the material that was to form the planets con-
densed out of the fringes of the cloud that was forming the solar system, set
up a whirling sub-cloud of
smaller condensations formed in
its
its
own. In some
outskirts to
cases,
become
still
satellites
of the central planet. If this is so, it is to
be expected that the
satellites
would
circle
THE SOLAR SYSTEM AND BACK
38 the planet
or quite near, the plane of the planetary equator
in,
and would do
Of
so directly.
the 32 satellites in the solar system
satellite of
queer combination of circumstances that 5),
no
less
than 20 do indeed
equator. Every 8;
is
less,
to the plane of the planetary
one of these 20 (Mars
and Uranus,
described in Chapter
circle their central planet in orbits
that are tilted by a degree, or
Saturn,
(including Janus, a
Saturn discovered in December of 1966 as a result of a
possesses
Jupiter,
5;
5) does indeed revolve directly about
its
2;
planet.
But what about the other twelve? These do not revolve
in the
plane of the planetary equator and might be termed the "anomalous satellites."
The
best example of an anomalous satellite
for its orbit
angle of
tilt
is
Some
is
our
own Moon,
considerably to our equatorial plane, the
varying from 18.5
Explanation:
Moon
tilted
over an 18.6-year period.
to 28.5
astronomers (and
myself) feel that the
I,
did not form out of the outskirts of the condensing cloud
that was forming the Earth and therefore does not have to circle
Earth in the
latter's equatorial plane.
been independently formed
Rather, the
Moon may
as a second planet in Earth's orbit
and was, eventually "captured" by Earth (see Chapter and Space and Other Things, Doubleday, 1965).
As orbit
7,
Of Time
rather impressive evidence for that, the plane of the is
tilted to
have
the ecliptic by only
5 °. It is
as
Moon's
though there was a
match the Sun's equatorial plane than the Earth's, and this is exactly what is to be expected of a body that was a planet in its own right and a satellite only by later accident. Despite the tilt, the Moon's revolution about the Earth, greater impulse for
it
to
or about the Sun, whichever
way you want
The remaining anomalous Jupiter, 7; Saturn, 2; Jupiter's five
equatorial plane
and
it, is
direct.
satellites are distributed as follows:
and Neptune,
innermost
to view
2.
We
satellites all
can begin with Jupiter.
revolve in the planetary
in orbits that are nearly circular.
Not
so the
BACKWARD, TURN BACKWARD— seven outermost, which are
officially
39
known only by Roman
nu-
merals in the order of discovery. All are small, with diameters ranging from a possible 10 miles to a possible 70. All have orbits that are both markedly tilted to Jupiter's equator
and markedly
eccentric.
They
fall
two groups. Three of
into
VII, and Jupiter
X—all
over 7,000,000 miles.
circle at
(Compare
of Jupiter's five equatorial
them—Jupiter
VI, Jupiter
an average distance of a with
this
satellites,
Callisto, the
which
is
only a
little
outermost over
trifle
1,000,000 miles from the planet.)
The
remaining four—Jupiter VIII, Jupiter IX, Jupiter XI, and
XII—have
Jupiter
orbits at average distances of
to 15,000,000 miles. Jupiter VIII has the
any of the Jovian
satellites.
from 13,000,000
most eccentric orbit of
approaches to within 8,000,000
It
miles of Jupiter and recedes to as far as 20,000,000.
The is
orbital tilt of the inner three of the
about 30
orbital
tilt
anomalous
or so, and their revolutionary motion
of the outer four, however,
(rather close to case
C
in Figure 4)
and
is
satellites
The
direct.
is
something
their orbital
like
160
motion
is
retrograde.
There are two questions. volve in retrograde fashion? into an inner group that
Why And
any do, why
direct
all
is
should any of the
if
this
satellites re-
odd
division
and an outer that
is
all
retrograde?
Explanation: Astronomers are generally agreed that the seven
anomalous Jupiter
is
satellites
of Jupiter are captured asteroids. After
at the outer fringes of the asteroid belt
sional asteroid, passing closely
gravitational field.
The
account for their small ture
would account
by
it,
could be trapped in
its
asteroidal nature of the satellites size
for the
all,
and an occagiant
would
and the random nature of their capmarked tilt and eccentricity of their
orbits. It
can be shown that
asteroid
moving
there are
more
it
is
easier for a planet to capture
an
in retrograde fashion than in direct. Ordinarily,
asteroids
moving
direct than retrograde
and
if
the
THE SOLAR SYSTEM AND BACK
40 approach asteroid,
close
is it
will
enough
to allow the planet to pick
be direct ones that
up any
most probably be captured
will
(like the inner three).
Borderline approaches, however, where Jupiter's gravity just barely counterbalances the Sun's, will not yield a capture unless
the asteroid can
slip into
a retrograde orbit, and that accounts for
the outer four.
If we pass on to Saturn, we find the same situation. Of its ten known satellites, the inner eight are equatorial, and the outer two are anomalous. Whereas the outermost of the eight equatorial
satellites
tenth
(Hyperion)
(Iapetus
is
900,000 miles from Saturn, the ninth and
and Phoebe)
8,000,000 miles from Saturn. dle size, however, with
Phoebe perhaps
The anomalous
about 150
and
and
satellites are of
mid-
800 miles across and
Iapetus perhaps
200.
Again, the inner anomalous Saturn's equator
2,200,000
respectively,
are,
and is
has a
satellite
revolves directly.
The
tilt
of about io° to
outer one has a
tilt
of
clearly retrograde.
Explanation: This would be identical to the one in the case of Jupiter.
That brings us to Neptune's two anomalous.
The
outer one, Nereid,
satellites,
both of them
a small body, perhaps 200
is
miles in diameter. It has an exceedingly eccentric orbit, the most eccentric orbit of any object in the solar system except for various
comets.
The
eccentricity, 0.76, allows
it
to approach
Neptune
to
within 800,000 miles and to recede to a distance of over 6,000,000. Its orbital tilt to
the plane of Neptune's equator
small enough to keep
its
motion indisputably
is
marked but
is
direct.
Explanation: Nereid, too, must be a captured asteroid, though
we might wonder how tune could capture
it
it
managed
in direct
great distance of the Sun,
to get out that far.
motion
is
That Nep-
probably thanks to the
which reduced the competing
solar
BACKWARD, TURN BACKWARD— Even
gravitational pull considerably.
41
the extremely
so,
elliptical
made
probably indicates that Neptune just barely
orbit
the
capture.
And
Neptune's inner
somewhat
larger
satellite,
Triton?
own Moon, and
than our
a large satellite,
It is
it circles
Neptune
in
a nearly circular orbit at the small distance of 220,000 miles
own Moon from
(about the distance of our
own Moon, Could
it
it is
be
not an equatorial our
that, like
Moon, was captured by
but
satellite,
is
%
which seem
satellites,
anomalous.
is
One
larger brother?
its
fact that tends
Moon
that the
is
like
largest of the satellites in terms of the
mass of the planets they Earth, and Triton
our
like
be that Triton,
it
to increase the plausibility of this suggestion
and Triton are the two
And,
Moon, Triton was an independent
planet forming in Neptune's orbit? Could
the
us).
The Moon
circle.
o
%
is
the mass of the
the mass of Neptune. All the equatorial
have been formed as part of the
surely to
planetary system to begin with and could never possibly have
been independent planets, are much smaller in terms of their planets.
But
if
this
orbital plane is.
were
That would
is
would be nice
Moon's
it
not
which
Un-
that touch of the independent planet. so.
The
plane of Triton's orbit
to the ecliptic (and almost as
tune's equator,
to discover that Triton's
least fairly close to the ecliptic, as the
give
fortunately, this
220
so, it
was at
is
much
tipped somewhat
itself
is
tipped
to the plane of
Nep-
to the ecliptic).
This means that Triton revolves in retrograde fashion about Neptune.
Why
should that be?
Explanation:
may have another
The
only one I've ever heard
taken place. Pluto
satellite. Its
is
may once have
that a catastrophe
circled
period would have been 6.7 days
rotational period, see
(its
Chapter 8) and that would place
little
farther out than Triton,
Some
event
may have
Neptune
which has a period of
forced Pluto out of
its
orbit
it
as
present
only a
5.9 days.
and into an
dependent planetary one (of unusually high eccentricity and
intilt
THE SOLAR SYSTEM AND BACK
42
major planet) and the same event
for a
may have
What
tilted Triton's
the event
may
Having done with revolutions about the Sun, how about
rota-
orbit into
present retrograde position.
its
have been, though, no one can suggest.
tions about
an
axis?
I
have already said that the
Sun
rotates
about
axis directly.
its
Ideally, every
body
in the solar system
with their equatorial planes ecliptic.
To
put
it
all
more
ought to do the same,
or less coinciding with the
another way, their axes of rotation ought to be
exactly perpendicular to the ecliptic. This
case of Jupiter, which
has
is
almost true in the
from the
tipped only 3
axis
its
perpendicular.
Our Moon's north lesser extent,
axis
pole
(and of Jupiter about
However, the
is
Moon
is
its
clear data.
We have determined
rotation.
about
its
direct.
is
say nothing of asteroids) are too far
on
Moon
rotation of the
axis)
the only nonplanetary body concerning
we have
the rotation of which
tipped to the ecliptic by an even
and the
only 1.5
The
away
other satellites (to
for
good information
periods of rotation for Mercury
and Pluto but don't have decent data on the orientation of
their
axes of rotation.
What
about the remaining seven planets, however?
mentioned
Jupiter;
and Earth's North Pole,
tipped through an angle of 23.5 ecliptic.
That
is
what
we
as
I've already
know,
all
is
from the perpendicular to the
gives us our seasons,
makes the days and
nights vary in length through the years, accounts for our climatic zones,
and
so on.
However, the
fact that the Earth's rotation
Other planets have Saturn, 27
;
situation here
polar
tilt
rotation
and is
But why
is
not enough to
tilt.
For Mars,
it is
directly,
.
is
that direct motion ceases. For
only tilts
retrograde (see Figure 5). is it
alter the
direct.
a similar polar
All rotate Neptune, 29 the same as for orbital planes. It for
reaches 90 is
is
tilting
that there should be an axial
tilt
at all?
25
;
for
for the
when
the
over 90
,
BACKWARD, TURN BACKWARD— Explanation:
I
know
don't
43
of any official explanation, but a
thought has occurred to me. As the planets form out of the
and
original cloud of gas
large
dust, they
would eventually form
several
chunks which would, for a while, be a "multiple-planet."
Circling in complex orbits they might eventually striking each other off center.
Might
come
together,
not be that the random
it
coming together might end by imparting a bit of "English" to the which would be reflected in the axial tilt?
direction of rotation
Or is this mechanically impossible? Unfortunately, I don't know. And even if this is so, the real surprise is the close correspondFigure
5
Axial Tipping CASEC
ence between the polar
and Neptune. Can
The
90»TIP
25° TIP
0°TIP
this
tilts
180' TIP
of four planets: Earth, Mars, Saturn,
be pure coincidence and nothing more?
planet Uranus has a very odd rotation; for the
Uranus's north pole
is
98 °. This
is
past the 90
mark
tilt
of
so that peo-
ple (even astronomers) usually say that Uranus has a retrograde rotation.
But
it is
call it that. If is
not very retrograde at
you look at Figure
close to that of case
5,
all,
and
it is
misleading to
Uranus's manner of rotation
C. (Jupiter's corresponds roughly to case
and that of Earth, Mars, Saturn, and Neptune, roughly B.)
A
to case
THE SOLAR SYSTEM AND BACK
44
Uranus actually
on
rolls
its side,
direct or clearly retrograde (and
so to speak,
it is
this
I
and
had
is
not clearly
mind when
in
I
argued against indiscriminate use of these terms early in the chapter).
Whatever managed
to
tilt
Uranus's
must have done
axis,
before the planetary system was entirely formed, for the satellites of
circle in
Uranus had
Uranus's
their orbits twisted to correspond
far-tilted equatorial plane.
equatorial satellites of Mars, Jupiter,
so five
and
For that matter, the
and Saturn follow the
tip of
the pole of their planets, too.
Explanation:
I
can only say that off-center collisions produced
a right-angle twist in Uranus's motion. This
weak
suggestion,
I feel,
And now we come known about Venus's
but
to
an extraordinarily
can think of nothing
Venus. Until
recently,
period of rotation or of
One
absolutely nothing.
I
is
else.
nothing was
its
tilt-
axial
simply couldn't see through the clouds,
and the clouds themselves had no markings that could be followed around the planet
There were
as
it
rotated.
guesses, to
be
sure,
and mistaken observations. The
period of Venus's rotation was suggested as anything from 24
hours (like that of the Earth) to 225 days tion). to
its
The consensus was
(its
period of revolu-
that Venus's period of rotation was equal
period of revolution and that, like Mercury,
it
faced one side
forever to the Sun.
But then radar measurements were taken showed that Venus did not face only one
in
1964 and these
any more
side to the Sun,
than Mercury did (see the preceding chapter). Venus's period of rotation turned out to be 243 days, a little longer than period. It
about
its
was the
first
case ever discovered of a
axis in a period longer
its
orbital
body rotating
than that in which
it
revolved
about a central body.
What's more, Venus's north pole was so that
its
case was very
much
tilted at
like that of case
D
an angle of 177 in Figure
5.
,
This
BACKWARD, TURN BACKWARD— meant that Venus's
rotation was retrograde— not fake retrograde,
but
as in the case of Uranus,
we must
Obviously,
real retrograde.
How
ask why.
can Venus, in the process of
Why
formation, have been tipped over completely?
standing on
The
head?
its
45
should
planet-making might account for a 25
final stage of
it
be
notion of off-center collisions in the tilt; it
might
account for a 90 tilt—but a complete 180 tilt? Astronomers are bound to look for something else. Perhaps the
just possibly
effect of
some other body it to take on
as to cause
suspect effect
the Sun, for
is
would
The
1
natural
Venus and
Venus
body
to
gravitational
its
all others.
Venus ought
to have a day that
closely the period of its revolution. If it faces
to the Sun, then
Or
rotation.
close to
it is fairly
swamp
surely
odd
the Sun, though, then
If it is fits
in the solar system so influenced this
Venus-rotation would equal
one
side always
Venus-revolution.
1
there might be something like the case of Mercury where
Mercury-revolution
is
equal to 2 Mercury-days
1
(from noon to
noon). Let's check the length of the Venus-day, then,
from noon to
noon, according to the method described in the preceding chapter.
With
a 243-day rotation about
motion of the Sun is
in the sky of
36o°/243 or 1.48
a negative sign and
Since there daily
is
.
Since the motion
make
is
that
— 1.48
axis,
the apparent daily
as a result of that rotation is
retrograde,
we must have
.
a 225-day revolution about the Sun, the apparent
motion of the Sun
olution
its
Venus
in the sky of
36o°/225 or 1.6
a negative sign so
.
we make
A
Venus
as a result of that rev-
direct revolution
that
— 1.6
must
also involve
.
Adding the two figures, — 1.48 and — 1.6 This means the Sun moves from west to east
,
we have (if it
— 3.08
were east to
west as with us there would have been a positive sign, +3.08 a
little
over 3
noon
)
each Earth-day.
The Sun would make to the next
negative sign
.
still
noon
a complete circuit of Venus's sky, from in 360
/— 3.08
or
—117
days,
where the
stands for a west-to-east motion of the Sun. Con-
THE SOLAR SYSTEM AND BACK
46
we end by
sequently,
saying that
Venus-day
1
equal to 117
is
Earth-days (with the Sun moving in opposite directions in the
two
cases).
This means that the Venus-year
which
not a very even
is
But consider This
this.
The
1.835
is
Venus-days long,
figure.
Venus
synodic period of
584 days long.
is
moments
the period (see Chapter 1) between successive
is
when Venus
is exactly between Earth and the Sun. But then, the synodic period of Venus is almost exactly
Venus-days long. This means that every time Venus
is
5
exactly
between us and the Sun, the same side of Venus, exactly the same side, faces us. It is as
though Venus's period of rotation
But how can that be? an
is
linked
somehow!
to Earth
How
can Earth's puny gravitation have
on Venus that would supersede the Sun's giant
effect
Surely this
is
pull?
impossible?
Explanation: Astronomers are trying to figure this out, but
would
like to
advance
my own
theory.
I
wonder
if
Venus's rota-
tional period has, perhaps, not yet reached equilibrium;
not yet reached a is
slowly speeding
final value.
up under the Sun's influence and
The
tion.
result
Venus-days in
1
its
Its
will,
some
day,
period of rotation will
would then be that there would be
exactly 2
Venus-year. This would be just the case that ex-
on Mercury, except that Venus would do rotation and Mercury by direct rotation. its
has
period of revolution, but in the opposite direc-
ists
As
if it
Perhaps, Venus's rotational period
reach a period of 225 days retrograde.
then be equal to
I
for the apparent connection
it
by retrograde
between Venus's rotation and
synodic period—well, there are coincidences in the universe,
and
think this
I
is
one of them. The thing to do
is
to continue
measuring Venus's rotation as accurately as possible and see there
is
a slow but steady speeding
up
years.
And
if
there is—well, you heard
it
if
of that rotation over the
here
first.
LITTLE LOST SATELLITE
4
The
older one gets, the
This year, as
my
it
more one tends
happens,
celebrate (if that's the
I
thirtieth anniversary as a professional
unbelievable to
me
since
it
to reminisce,
seems to
me
I
suppose.
I
word
I
want)
writer— something quite
am
not very
much more
than thirty years old.
To emphasize right of
this fact, I
an even dozen of
when one
have already had to renew the copy-
my
early science-fiction stories,
begins renewing copyrights,
it
upon the doorstep. So my mind keeps turning back, more than it used first science-fiction story I ever sold— back in October of face it— late youth
is
receipt of the letter of acceptance, with enclosed check,
to, to
1938.
I
couldn't very well frame the check for
I
framed the letter
my
word.
letter.
life.
needed the money, so
letter of acceptance.
modesty
made
intact.
A visitor would
the wall?" and visitor
my
was written with a dead ribbon on gray paper and
only a close scrutiny
kept
I
the
The
from Ray
Palmer of Amazing Stories was one of the high points of
The
and
becomes necessary to
I
I
ask,
it
legible at
all.
This was good, since
it
didn't have to say a single vainglorious
"Why
would merely
have you got an empty frame on say, "It isn't
empty."
Then my
would automatically approach the frame and read the
THE SOLAR SYSTEM AND BACK
48
Best advertisement a modest fellow ever had.
The name
of that
first
story
was "Marooned
never done an essay about Vesta, which I
now ought
So
to.
I will;
generally, for Vesta, as
The
asteroid to
first
No, that
and we
will begin
be discovered was,
would be natural to see the case and I will come back to
it
error.
largest
Vesta."* I've
and
well worth one,
with the asteroids
you undoubtedly know,
not a typographical
is
is
off
an
is
asteroid.
surprisingly, the largest.
You might first,
well suppose that
but that
isn't so in this
it later.
This discovery took place on January
1,
1801, under circum-
Of Time and Space and Other
stances described in Chapter 9 of
Things (Doubleday, 1965), so I won't go into detail here. A second asteroid was discovered in 1802, a third in 1804, and a fourth in 1807,
was
how
and there
it
stopped. For thirty-eight years that
matters stood, and astronomers,
finding four objects in
what was
who had been
rattled at
essentially a single orbit, settled
down.
But you can always count on one troublemaker and it
in this case
was a German astronomer, Karl Ludwig Hencke, who,
decided he would scour the heavens and see fifth.
Year
he found
after
it.
in 1830,
he could find a year he searched and searched and then in 1845
And
in 1847,
he found a
sixth,
if
while the English
as-
tronomer, John Russell Hind, found a seventh and eighth. After that,
it
was
just
Some 1600 had
a rat race.
asteroids are
their orbits plotted,
now
and
sufficiently well
it is
known
to have
estimated that there are about
44,000 asteroids with diameters of more than a mile, and heaven
knows how much rubble less than But never mind the thousands. those
first
a mile in diameter. I
am
going to concentrate on
four asteroids which, between 1807 and 1845, existed
in lonely splendor in
the consciousness of astronomers. Their
names, in the order of discovery
are:
Ceres, Pallas, Juno,
and
Vesta. * Included in
AsimoVs Mysteries (Doubleday, 1968)
if
you are curious.
LITTLE LOST SATELLITE As
figures
I
can find for their diameters are
Table
It
listed in
Table
The
best
1.
1
Asteroids
Diameter ( miles
Ceres Pallas
470 300
Juno Vesta
240
120
seems quite certain that no other known asteroid has a
diameter of as
much
240 miles, so Ceres, Pallas, and Vesta are
as
the three largest asteroids in that order, pretty tion.
49
happens, these are large bodies as asteroids go.
it
A
number of
asteroids,
much beyond
ques-
however, are very likely to have
diameters between 120 and 240 miles and some have actually been estimated (with considerable uncertainty)
to
be
in that range.
However, by virtue of time of discovery and position of
orbit,
Juno makes a natural fourth and we can speak conveniently,
if
not entirely accurately, of the "Big Four."
The Big Four have those of
Mars and
perfectly ordinary orbits, firmly
Jupiter.
Some
Table Asteroids
Eccentricity
(millions of miles)
of Orbit
Juno Vesta
The
closest
farthest
(perihelion)
(aphelion)
237
278
0.079
197 184
319 310
0.258
206
239
0.088
257 257 247 219
Pallas
orbit of Ceres, as
of 0.079
is
less
you
see,
is
2.
2
Distance from the Sun
average
Ceres
between
of the details are given in Table
0.235
nearly circular. Its eccentricity
than that of Mars. What's more,
its
mean
distance,
THE SOLAR SYSTEM AND BACK
5o
257,000,000 miles, all
is
the asteroids whose orbits are known. Vesta's orbit
slightly less circular is.
very nearly that of the average distance of
and
distinctly closer to the
it is
Vesta's farthest point from the
Ceres' closest point.
Four, that
in
is
As
Table
Sun
far
from
it
for the period of revolution of the
only
as
is
Big
3.
Table
3
Period of Revolution
Asteroids
(days)
Pallas
about as
is
is
Sun than Ceres
(years)
Ceres
1680
4.60
Pallas
1686
4.61
Juno Vesta
1593
4.36
1325
3.63
and Juno, from the data given
in
Table
may make
it
sound as
nearly identical orbits. This particularly, are too close
and are going
Not at all. The orbital diagrams you
2,
to collide
seem to have if
these two,
one of these
days.
usually see in astronomy texts are
two-dimensional projections of a three-dimensional are tipped
by
ecliptic), as
different
shown
in
amounts Table
reality.
Orbits
to the plane of Earth's orbit (the
4.
Table 4 Asteroids
Tilt to Ecliptic
(degrees)
Ceres
10.6
Pallas
34.8
Juno Vesta
13.0 7-i
two dimensions, the orbits seem to cross, a threedimensional model would show one crossing far above or far be-
Where,
in
low another. There future.
is
no danger of
collision in the foreseeable
LITTLE LOST SATELLITE
51
customary to consider the asteroids as small
It is
fry
and dismiss
them. Indeed, the most nearly proper name given them by astronomers
"minor planets." But that
is
An
tric classification.
with considerable Saturn, Uranus,
inhabitant of Jupiter might, after
justification,
four planets
just
list
and Neptune) and put everything
Earth on down, into the "minor planet"
So
a purely anthropocen-
is
all,
else,
from
classification.
to consider the Big Four, at least, as objects
let's try
and
(Jupiter,
of individual consideration and see what
we can
worthy about
find out
them.
is
Some have
estimated that the total mass of
about
that of the Earth, or about
%o
only a rough guess, of course, but
let's
This
is
mean
%oo
all
the asteroids
that of the
use
it.
that the total mass of the asteroids would be about 8,500,-
000,000,000,000,000 tons.
The
individual masses of the Big
rough guess) are as shown in Table
(also a
Table Mass
Asteroids
From
5
Per Cent Total
(tons)
Ceres
850,000,000,000,000,000
10.0
Pallas
220,000,000,000,000,000
2.6
Juno Vesta
14,000,000,000,000,000
0.2
110,000,000,000,000,000
1.3
the standpoint of mass, then,
though there
is
only a "Big
second largest
One"— Ceres.
satellite
contains one-tenth of
all
Four
5.
Asteroid
as the
Moon.
This would
it
would
It is
and, within
its
Mass
really
seem
as
four times as massive
own
small sphere,
it
the asteroidal matter. Together, the Big
Four make up one-seventh of
all
the asteroidal matter.
we had reached the Big Four and decided up a base on one of them. What would things be like at such a station? First, how far away would the horizon seem? As it happens, the distance of the horizon from some given low Suppose, next, that
to set
height above the surface
is
proportional to the square root of the
THE SOLAR SYSTEM AND BACK
52
diameter of the planet. Since the diameter of Ceres
Y17
is
just
about
that of the Earth, the distance of the horizon on Ceres would
be about %.i that of the horizon on Earth. If we were standing on the surface of a large
and were of average height
flat
so that our eyes were
plain
5%
on Earth
feet
above
ground, the horizon would be about 16,000 feet away (just over 3 miles)
.
Supposing the Big Four to be smooth spheres, the horizon
distance on
them would be
as
shown
Table
in
6.
Table 6 Distance of Horizon
Asteroids
(feet)
Ceres
4000 3100 2000 2800
Pallas
Juno Vesta
It seems to me this is an important point. The dome of the sky would come down and meet the ground on Ceres, along a circle much closer to your eye than it does on Earth. What's more, on Earth, the presence of an atmosphere dims
objects
on the horizon and turns them
tops of hills and mountains of course, this
and they
mistiness as
When usual,
the air
we
On
is
much
are all the mistier
a
way
very clear
bluish.
(We
can see the
farther than 16,000 feet away,
and bluer
for that.)
of unconsciously estimating
and distant
objects
We use distance.
seem sharper than
automatically think they are closer than they really are.
Ceres, where there
is
no atmosphere, the objects on the
horizon would be sharply outlined. Even the tops of crags farther
than 4000 feet away would be sharp.
We would therefore estimate
the horizon on Ceres to be closer than
me
certain, then, that the
even more so on
men
better
actually
is.
It
seems to
on Ceres (and would be subject to
establishing a base
the other asteroids)
Some, who are used to wide-open might not be able to make it; perhaps the asteroids had
claustrophobic uneasiness. spaces,
it
be
staffed
by
city boys.
LITTLE LOST SATELLITE
53
In another way, the Big Four are not so small after
all.
What
about their surface area?
Table 7 Surface Area
Asteroids
(square miles)
The
Ceres
700,000
Pallas
280,000
Juno Vesta
180,000
45,000
surface area of Ceres
is
just
about
as
large as that of
Alaska plus California. Even the surface area of Juno, the smallest of the four, of
all
four
equal to that of
is
New
York
State,
equal to one-third that of the
is
and the
fifty
total area
United
States.
room to explore on the Big Four and, for that matter, plenty of room to get hopelessly lost in. The question of surface gravity may make the Big Four seem small again. If two spherical bodies are of equal density then the There
is
plenty of
surface gravity
is
proportional to the diameter. If
we assume
that
the Big Four are essentially rocky in character, then they probably have the
the
Moon
same density
as the
Moon. The
(2160 miles in diameter)
In that case,
we can
prepare Table
is
surface gravity of
0.16 that of the Earth.
8.
Table 8 steroids
Surface Gravity (per cent of Earth's)
A
180-Pound Man Will Weigh (pounds)
Ceres
3.5
6.3
Pallas
2.2
4.0
Juno Vesta
0.9
1.6
1.8
3-2
This looks
like a set of feeble grasps indeed. Is it possible that
a person, making a careless move, might shoot upward and away
THE SOLAR SYSTEM AND BACK
54
from the
satellite altogether?
him and would he be it is
Would
the feeble gravity
To
lost in space?
fail
to hold
danger of that,
test the
only necessary to calculate the escape velocity.
Table 9 Escape Velocity
Asteroids
miles/ second ) (
(
miles/ hour )
Ceres
0.33
1200
Pallas
0.2 i
Juno Vesta
0.08
750 300 600
0.16
These values are not high compared to Earth's escape which
is
6.98 miles per second, or 25,000 miles an hour.
velocity,
even
Still
on Juno, the baby of the four, one would have to move at a speed of 300 miles per hour to lift off the asteroid. You are certainly not going to jump upward at that speed. to drive a
by the
asteroid,
seem, will do
But now
and the
its
satellite to
to
is
be the
are not even going
will therefore
gravitational force, small
be held
though
it
may
essential job.*
let's raise
the question of the order of discovery.
at the start of the chapter, that
prising
You
ground vehicle at that speed. You
be discovered was the
it
largest.
that you would expect the brightest,
and the
largest
is
I said,
was surprising that the
The
reason that
first satellite
to
is
first
sur-
be discovered
not necessarily the brightest.
Being large helps, of course. All other things being equal, a large
body catches more sunlight than a small one and
But are
all
other things equal?
matters: distance
Two
factors in particular
is
brighter.
may
affect
and albedo.
was first written, a letter from Thomas McNelly of Corgave me some calculations as to the influence of the centrifugal effect introduced by the possible rotational periods of the asteroids. At the equator, the gravitational pull might be reduced from 5 to 10 per cent, and the escape velocity from 30 to 40 per cent. You would still remain securely on the asteroid but by a narrower margin than I had originally assumed. * Since this article
nell
LITTLE LOST SATELLITE It is clear that
light
catches and the less bright
it
Mars ought
orbit of
55
the farther from the Sun an asteroid
A
it is.
is,
be brighter than a considerably
to
the less
small asteroid near the larger as-
teroid near the orbit of Jupiter,
and the smaller one ought then
be discovered sooner than the
larger.
But
as
it
to
happens, the Big Four are moderately close to us as
asteroid distances go,
and there are no reasonably
are markedly closer than they are. It
is
large ones that
not to be expected then
that any asteroid will be discovered sooner than the Big Four
merely because of a distance difference. Furthermore, the Big Four themselves are not at markedly
enough
different distances; not
any
different, at
rate, to
overcome
the size differential. Eliminate distance, then.
What
about albedo?
Albedo is
is
the fraction of the light, received by a planet, which
then reflected. Thus,
if
a planet reflects one-fifth of the light
from the Sun,
it
has an albedo of 0.2.
receives
As
it
happens, the solid rock of a planetary surface
reflector of light.
and that
is all
exposed to direct sunlight (since there
than *4e of the light 0.06, and the same is true for Mercury.
phere present) albedo
A
is
The Moon, which
has a surface that
reflects less
cloudy atmosphere
is
much
is
is
it
a poor
is all
rock
no atmos-
receives. Its
it
better at reflecting light. Mars,
with a thin atmosphere and an occasional thin cloud, has an albedo of 0.1
5,
two and a half times that of Mercury and the Moon.
Planets with thicker atmospheres reflect an even larger fraction of the light they receive.
The albedo
of the Earth
is
0.40,
while that of the outer planets approaches the 0.50 mark. Venus's clouds do best of
all for
But with respect problem.
It
some
reason,
passes the
bounds of
asteroid should be able to retain asteroids,
generally,
and
its
albedo
is
about 0.70.
to the asteroids, the albedo should raise
as
belief
that even the largest
an atmosphere.
composed of
no
rock,
all
If
we
consider the
should have an
albedo of 0.06. (Indeed, asteroids other than the Big Four have
THE SOLAR SYSTEM AND BACK
56
their diameters calculated
from
known
their
and
distance
bright-
ness by assuming this albedo.)
we can
Therefore, factor.
with
We can
would seem) eliminate the albedo
(it
expect the brightness of the Big Four to decrease
and therefore we can expect that chances are the Big
size,
Four would have been discovered
The apparent magnitude 7 2.5
X
is
in order of size.
brightness of an astronomical
magnitude, which
in
2.5 times as bright as
2.5 or 6.25 times as bright as
we
consider the
first
measured
is
is,
a body of
one of magnitude 8 and
one of magnitude less
and
9,
Table
is
so on.
the brightness.)
three asteroids to be discovered,
works out neatly, as seen in Table
Asteroids
body
That
a logarithmic scale.
is
(Notice that the higher the magnitude, the If
as a
all this
10.
10
Diameter
Magnitude
Brightness
(miles)
(closest to
(]uno
= i)
Year Discovered
Earth) Ceres
470 300
74
3.3
1801
Pallas
8.0
1.9
1802
Juno
120
8.7
1.0
1804
Ceres, the brightest of the three,
be seen by the unaided it,
so
then
you might suppose
which
Pallas,
which
is
is
it
is
too dim, at
its
brightest, to
but even a small telescope only right that
it
was
first
will
show
discovered;
over half as bright as Ceres; and then Juno,
over half as bright as Pallas.
But Vesta it
eye,
is
and should be
larger than Juno,
brighter.
Why was
discovered only in 1807, three years after Juno? It can't be dis-
tance because
it
is
albedo. Perhaps, for
rock and
is
Yet that
even closer than Juno. Perhaps then,
some
reason, Vesta
dimmer than Juno is
is
it
is
composed of darker
despite the larger size of the former.
not so either. In
fact,
being greater than that of Juno,
is
Vesta's magnitude, far from
not only
less
than Juno's but
LITTLE LOST SATELLITE
57
than that of Pallas and even of Ceres. Vesta has a magnitude,
less
which means that
at closest approach, of 6.5,
times as bright as Juno. It
To
put
it
most
is
sharply, Vesta
the brightest of
is
less
than 7.5
the asteroids
all
be made out on a dark, moon-
and
at
less
night by someone with excellent eyes.
its
no
it is
even 2.3 times as bright as Ceres.
brightest can just barely
It is
the only asteroid
that can ever be seen with the unaided eye.
Why,
then, did
take so long to discover Vesta?
it
Ceres was discovered by accident. for
wasn't looking
Its discoverer
any planetary body and he happened to spot Ceres, the second
brightest asteroid. That's reasonable enough.
before they found the
But zling
Why
why Vesta
after
surface area of Vesta
more
light, it
all.
What
is
about
%
just
is
is
should be about
a
%
trifle
means that
The albedo
high.
puz-
it
is
is
Sun and Ceres if the two
actually
must have an albedo that
of Vesta, in fact,
that of Ceres.
closer to the
as bright as
were of equal albedo. The fact that Vesta as Ceres
much more
should be so bright.
Allowing for the fact that Vesta gets
they found Pallas and Juno
is it
much brighter Vesta—years before?
minor mystery,
that's a
is
The
group of astronomers searched
for six years after that, a
Still,
intently for other asteroids.
%
as bright
seven times as
is
possibly as high as 0.5, a
value equal to that of planets with deep, thick atmospheres.
But Vesta
can't have a deep, thick atmosphere.
maining alternative
is
that
it
of ice (or possibly frozen carbon dioxide)
fields
face, reflecting,
The
only
re-
has an icy surface; that there are
on Vesta's
sur-
with considerable efficiency, the feeble light of the
distant Sun.
But
if
that
is
so,
where did the
there be only one asteroid out of
Or
is it
just
asteroids? Is
it
one?
Is it
all
ice
come from?
those thousands that
possible that there are a
just that of
whole
the four, whose diameter
have measured directly with
fair
Why
accuracy, only one
that gives us a false impression of uniqueness?
is
should icy?
class of icy
we happen
is icy,
to
and that
THE SOLAR SYSTEM AND BACK
58
had
All the other asteroids have
on the assumption of
a
determined
their diameters
low albedo. Suppose a number of them
have high albedos and are considerably smaller than we assume. Perhaps an original asteroid-planet exploded,
its
interior form-
its
core,
ing stony asteroids (with a few nickel-irons from
one)
while
surface
ice-encrusted
its
asteroids; with only
Vesta
had
if it
gave birth to Vesta-type
of that type, clearly visible.
itself,
But there are problems. Would the catastrophe leave the ice on Wouldn't the ice be blown off or melted
a surface fragment intact? off
by the energies released by the explosion, and distributed
And would
through space?
the fragment, undoubtedly irregular
now
to begin with, coalesce into the fairly spherical shape Vesta has, with ice remaining
on the surface rather than folding into
the interior?
And
the explosion theory
if
is
eliminated,
what
the alterna-
is
tive?
One
suggestion
asteroid at
all,
to begin with
tion
and
it
is
that Vesta
but a displaced
it
unique, because
is
satellite. If it
would have been a sphere from
might have picked up an
mosphere of the young planet
it
was
ice layer
circling.
it
had been its
is
not an
a satellite
time of forma-
from the outer
at-
Then, somehow, the
satellite
was pulled away from the planet and went wandering
off, lost,
in the asteroid belt.
If s a touching picture of a its
original planet
belt are Jupiter
have been?
little lost satellite,
The
but what would
closest planets to the asteroid
and Mars. Could Vesta have once been a
satellite
of Jupiter?
We
have one piece of information that might help us decide.
In 1967, careful measurements of the brightness of Vesta were
made and
a tiny variation with a period of
Supposedly, this represents of
its
surface
may be
less
its
5%
hours was reported.
period of rotation, for
some
the relatively rocky side shows, the albedo drops and with brightness; as the icy side shows, both go back is
parts
densely covered with ice than others. As
repeated over and over.
up
again;
it
and
the this
LITTLE LOST SATELLITE Such a rotation ought to represent Vesta's revolution about a planet; for
had been
if it
very likely have presented but one face to
a rotation equal to
For a
its
its
59
original period of
a satellite,
period of revolution, like our
satellite to circle Jupiter in
5%
it
would
planet and have had
hours,
it
own Moon.
would have to be
64,000 miles from Jupiter's center, or only 20,000 miles above
cloud layer—much closer than Jupiter's closest present
its visible
satellite.
A
position— even
satellite in that
of
strain
vast
Jupiter's
could withstand the tidal
if it
gravity—couldn't
possibly
have
been
snatched away from that planet's enormous grip by any reasonable
mechanism. Even
away an
some unimaginable catastrophe had ripped from Jupiter, how could it have done
if
inner-satellite-Vesta
so without disturbing Jupiter's other inner satellites?
(How
can
we
the other inner
tell
Well, Jupiter's
five
perfect circles
and almost exactly
plane,
much
circle
Mars
miles above
better.
To
surface. It
Phobos or Deimos and
it
if
Mars, the situation would
5%
hours
would have
it
its
to
center, or 2400
closer to the planet than either
could not have been abstracted from
its
Phobos and Deimos, and those two
Vesta had been abstracted from anywhere by some
cosmic catastrophe, it
have never been
have not been disturbed.
Besides,
but
in almost
their formation.)
4500 miles from
would be
position without disturbing satellites
satellite of
it
the planetary equatorial
in
for satellites that
revolve in
at a distance of its
move about
from the moment of
Vesta were originally a
not be
weren't disturbed?
satellites
satellites
and that can only be true
seriously disturbed If
innermost
it
would very
doesn't, not particularly.
have an eccentric
orbit;
revolves just about
where
likely
And
it
a normal asteroid should. That's asking a lot of coincidence for a little lost satellite.
(On first
the other hand, Richard H.
Weil wrote me
appeared suggesting that Vesta
original
may be
the
after this essay satellite of
the
unexploded asteroid-planet, a most attractive suggestion.
THE SOLAR SYSTEM AND BACK
60
What's more, the well-known So there
is
that very fact, erally,
alas, I
a fascinating mystery about Vesta, it
may have more
and about the
James Blish had missed.)
science-fiction writer
used this hypothesis in a story of his—which,
and because of
to tell us about the asteroids gen-
solar system as a whole, perhaps,
than any
other body between Mars and Jupiter.
When
the time comes, then, that our
out beyond Mars at the port of
first call.
Vesta, please!
last, I
want
manned
spaceships head
to put in a strong suggestion for
B
— THE
OUTER SYSTEM
LITTLE FOUND SATELLITE
5
One week
ago (as
I
write this)
I
visited Brandeis University
a friend to look over a tremendous exhibit of old Bibles
they had on view.
with
which
We stopped at one fifteenth-century Bible, pub-
lished
by Spanish Jews, which was open to the seventh chapter of
Isaiah.
This contained the verse which, in the King James version,
reads in part, "Behold a virgin shall conceive,
The Hebrew word almah, which King James, was not translated ing
at. It
ters,
was merely
is
and bear a son."
translated "virgin" in the
in the Spanish Bible
transliterated
and
left
we were
look-
"almah" in Latin
a fact pointed out in the information card that
let-
accompanied
the exhibit.
My mah sion,
friend
wondered why that was
didn't really
the verse
mean
is
so
and
I
explained that
al-
"virgin." (In the Revised Standard Ver-
translated,
conceive and bear a son.") Yet
"Behold, it
a
young woman
would have been
shall
terribly dan-
gerous for Spanish Jews of that period to translate correctly and
seem
to
be denying the
leaving the
I'm afraid it
virgin birth, so they
evaded the issue by
word untranslated.
my
so often does
enthusiasm caught up with
when
I
am
me
at this point, as
trapped into explaining something.
THE SOLAR SYSTEM AND BACK
64
My
voice reached
oblivious to
my
my own
plain
normal window-rattling pitch and
its
surroundings. What's more,
I
I
grew
went on to
ex-
theories (at considerable length) as to the signifi-
cance of
this chapter of Isaiah and grew eloquent indeed. Finally, what must have seemed an eternity to my friend, I ran down and passed on to other items in the exhibit. The sequel was told me, with obvious delight, by my friend later.
after
It
seems a Pinkerton guard at the exhibit (which was valued
had been
at $5,500,000)
guard said to
my
my
friend,
listening to
I
passed on, the
such an expert?"* and
my name than "Do you know who he is?"
with greater faith in the weight of
friend,
myself have, said, portentously,
The guard thought Oh,
me. After
"What makes him
well, I
a
and
little
I
"God?"
said,
suppose that sort of thing
is
an occupational hazard
and I'm not going to practice my profession though
for the professional explainer
let it rattle
me.
I
I
lower
continue to
will
my
voice next time and, perhaps,
will try to
somewhat subdue
my
gen-
eral air of divine authority.
With
mind known
that in
Saturn was
let's
as
astronomical records. is
Its
take
up the subject of the planet Saturn.
one of the planets from the beginning of
magnitude at
its
brightest
then brighter than any star except Canopus and
easily seen,
even though
it is
ets at their brightest (see
What made
it
dimmer than any
Chapter
is
1).
remarkable, as far as the ancient astronomers
moved more
slowly against the back-
it
ground of the
than did any other planet.
a
fixed stars
complete
it
of the other plan-
were concerned, was that
made
—0.4, and
Sirius, so it is
circle of
The Moon
the sky in a month; the Sun in
1
year;
Jupiter in 12 years. Saturn, however, did not complete a circle of
the sky until 29.5 years had passed. * You may be wondering the same thing. I'm not, really, but I a rather big book about the Bible, the first volume of which was Doubleday in October, 1968, so I'm up on the subject. The title in case you can hardly wait to buy it, is AsimoVs Guide to the I
explain that the
title is
the publisher's and not mine?
have written published by of the book, Bible.
Need
LITTLE FOUND SATELLITE The Greeks
65
movement
interpreted this slow
to
signify that
Saturn was farther from the Earth than was any of the other
known
planets
slowly because fact that
it
to them. In other words,
was so
it
distant.
it
That would
seemed
to
move
so
account for the
also
was dimmer than the other planets.
In this, the Greeks turned out to be correct.
Of
course, they
had no way of knowing the actual distance of Saturn, but, on the average,
it is
about 887,000,000 miles.
It also, as a
matter of
fact,
moves more slowly about the Sun than any of the other visible planets do. Whereas Mercury's average orbital speed is 29.8 miles per second, and Earth's
is
moves
18.5 miles per second, Saturn
along at a mere 6.0 miles per second.
The Greeks
called the planet "Cronos."
ing Cronos are rather unpalatable.
He was
The myths
concern-
the son of Ouranos
(Uranus), the god of the sky, and Gaia (Gaea), the goddess of the earth. His parents had given birth to a series of monsters
whom
Ouranos
in horror
had imprisoned
in hell.
Gaia angrily
encouraged her non-monstrous son, Cronos, to take vengeance.
Armed with
Cronos crept up on
a sharp sickle,
his father
when
the latter was asleep, castrated him, and took over the rule of the universe.
But the crime had dren would serve him
its
as
aftermath. Cronos feared that his chil-
he had served
his father. Therefore, each
time his wife, Rhea, bore a child, Cronos would swallow nally,
when Rhea bore
Fi-
it.
Zeus, she deceived Cronos by giving
him
a stone dressed in swaddling clothes. Zeus was reared in secret,
and when he matured, he warred against Cronos, defeated him,
made him
disgorge his other children,
and then replaced him
as ruler of the universe.
The circles
up
planet
we
call Jupiter
was called Zeus by the Greeks.
the heavens in just under 12 years. Every 20 years,
to the planet Cronos,
so slowly,
it is
fitting to
and passes
name
it
for
an
it.
it
catches
Because Cronos moves
old, old god.
(And
the slow,
heavy motion gives us our word "saturnine.") Because Zeus forever overtaking
and passing
it,
It
the two seem forever to be
is
re-
THE SOLAR SYSTEM AND BACK
66
myth
enacting the old
of Zeus replacing his father
on the
uni-
versal throne.
The Romans
identified their god, Saturn,
an agricultural
with Cronos. (And perhaps they were right to do
may have been an
himself
he used
sickle
myth may
is
which
is
agricultural deity to begin with.
refer, symbolically,
to the harvesting of grain,
where
Cronos with Chronos,
Greek word and which means "time." For that reason,
a
the aged Cronos with his sickle
Time."
The
off.)
a strong tendency to confuse
is
deity,
Cronos
an agricultural implement and the castration
the fertile ears are cut
There
so, for
It is
used to represent "Father
mowing down we pedants
everything
lentless sickle
what time
is
an excellent representation, as
does, but
it
re-
a chilling picture of
is
consider
happens, for the
it
wrong
just the
same.
In July, 1610, the Italian astronomer Galileo Galilei turned his telescope
new
He had
on Saturn.
on the Moon, four stars
already discovered the mountains
on the Sun, and
satellites of Jupiter, spots
everywhere.
What
could he find out about Saturn?
His telescope was, of course, a primitive one, and Saturn was far
away. Galileo couldn't
make out
clearly
but he saw something odd. Saturn wasn't
what
just a
it
round
was he saw, ball, as Jupi-
was a bright something or other on either
ter was; there
side.
Galileo thought they might be a pair of subsidiary bodies, large
twin
satellites,
In 1612, urn,
one on either
when he had
he found the
disappeared.
He
side.
a chance to return to the study of Sat-
satellites
(if
that was
saw nothing but a round
what they were) had ball, like Jupiter,
only
smaller.
Galileo was quite upset. After
new
all,
the telescope was a brand-
instrument, and there were not wanting opponents
insisting that
what
it
made
visible
were merely
who were
illusions, sent
by
the devil to rouse doubt concerning the divinely inspired Biblical
account of the universe.
If
the telescope showed Saturn to be a
LITTLE FOUND SATELLITE body
triple
some times and
at
body
a single
6j
at others, that
would
indeed be a triumph for reaction. Galileo avoided looking at Saturn after that,
"Does Saturn swallow
a friend, asked, petulantly, (I
and
was once asked quite
seriously
in a letter to its
children?"
whether the Greeks might
have been able, somehow, to see Saturn plainly enough to make
and named the planet accordingly. Of course not! The Greeks had no telescope and it is as certain as anything can be this out,
that they never saw Saturn as anything but a point of light.
matter
is
a coincidence,
The
though a particularly interesting one.)
Nearly half a century later the Dutch astronomer Christian
Huygens, with better telescopes at Saturn. In 1655 ne discovered
began to study
his disposal,
had a
it
satellite
and named
it
Titan.
By the next
year,
he had puzzled out what
it
was that had so
make
upset Galileo. His telescope wasn't quite good enough to it
out with indisputable
clarity,
but he, too, could see something
extending out on either side of Saturn. Call
them
a pair of satellites, as Galileo
had done.
If that
were
then they would have to revolve about Saturn. That was a slightly risky deduction, for this was before Newton had advanced his law of universal gravitation which gave a sound theoretical basis for maintaining that a satellite must reso,
volve about
the four
its
planet.
satellites
Still,
If
Moon
revolved about the Earth,
of Jupiter each revolved about Jupiter,
Titan revolved about Saturn. satellites
the
Why
and
not suppose that Saturn's twin
followed the general rule?
these twin satellites revolved about Saturn, their appearance
should alter from night to night. Eventually one should be be-
hind Saturn and one in front so that both would be
Could see
them
this
be what accounted
in 1612?
No! The
invisible.
for the fact that Galileo didn't
visibility
and
invisibility periods
alternate at intervals of a very few days or even hours jects
were twin
The
satellites,
and not
if
should the ob-
at intervals of several years.
only way Huygens could account for the fact that the ap-
THE SOLAR SYSTEM AND BACK
68
pearance of the twin
satellites
remained unaltered
night was to suppose that there were a that there were always
some
some
number
for night after
of satellites so
in front
and back of the planet and
make
the appearance utterly con-
to either side. Indeed, to
ought to be in the form of a ring about the
stant, the satellites
planet.
But then how account
for the fact that the
appearance did
slowly change over the years and that the satellites disappeared utterly
from time to time?
Huygens reasoned that the
ring
might be a thin one which was
tipped to the plane of the ecliptic (to that of Earth's orbit, in other words). This
known
When rings
urn
Saturn
and
is
is
so,
and the angle of
inclination
is
now
to be 26 ° 44'. is
on one
them
see
side of
its orbit,
clearly in front
on the other
and again see them
and
side of the orbit,
we
look
down on
to either side.
we
When
the Sat-
look up on the rings
clearly.
we could watch Saturn every night as it swings from one end of its orbit to the other, we would watch the tipping of the ring begin at maximum-down to maximum-up over a period of 14% If
years as the planet goes
14%
years
goes back to
it
maximum-up
to
(Actually, the
from one end to the other. In another its initial
point and the ring shifts from
maximum-down. tilt
of the rings does not shift. It remains con-
stant with reference to the stars. This constant-tilt-with-referenceto-the-stars
combines with Saturn's motion around the Sun to
produce an apparent Earth. This
is
oscillation-of-tilt
with respect to the Sun, or
not easy to see in the mind alone, so maybe Figure
6 will help.)
Midway between must come
the maximum-up and maximum-down, there when the rings are seen exactly edge-on. The happens midway between the maximum-down and
a time
same thing the maximum-up. This means that every 14% seen edge-on. are not big
If
they are a thin,
flat
enough to magnify the
structure,
years, the rings are
and our telescopes
rings to the point
where the
LITTLE FOUND SATELLITE thickness
is
happened
69
perceptible— they will seem to disappear. That
is
what
to Galileo.
Figure 6 The Tilting of the Rings
SATURN'S ORBIT
Huygens put scrambled the
wanted
his discovery into a
letters
few Latin words and then
by putting them
to preserve priority
in alphabetical order.
if
he turned out to be
right,
reserving the privilege to withdraw without embarrassment
were wrong,
By
an
as did Galileo in
earlier case (see
Chapter
He
while if
he
1).
and he published the
1659, ne was convinced he was right
Latin sentence, which read "Annulo cingitur, tenui piano, nus-
quam
cohaerente, ad ecliptam inclinato." Translated freely,
says that Saturn it
is
anywhere, and
Huygens nothing
is
"surrounded by a thin,
tilted to
flat ring,
it
not touching
the ecliptic."
not to be blamed for his caution. There was simply
like Saturn's ring in the heavens,
It is absolutely
unique among
all
and there
still
the heavenly features
isn't.
we can
see.
What that all?
is
the ring?
It
appears to be a thin,
flat,
solid structure. Is
THE SOLAR SYSTEM AND BACK
70
Huygens's contemporary, the Italian-French astronomer Jean
Dominique
Cassini,
1672, he discovered
is
the next great Saturnian. In
two
1671
(Iapetus and Rhea)
satellites
1684 two more (Dione and Tethys) so that at that time turnian satellites were
And
He
cerning the ring. a third of the
known
he published
in 1675,
way
in
and
and
in
five Sa-
altogether. his contribution to
knowledge con-
detected a dark line curving around
it
from the outer edge. Huygens thought
about it
was
a dark marking
on a solid ring. Cassini thought it was a separaand that there were really two rings, one outside the other. The outer one we can call Ring A and the inner Ring B.
tion
Cassini turned out to be right, and the dark marking he dis-
covered
is still
As a matter of fact there none are so broad and easy to
called "Cassini's division."
are other divisions, too, though see as Cassini's.
Anyway, since 1675, we speak of the "rings" of
Saturn, not the "ring."
New
continued to turn up. In 1789, the German-
satellites
English astronomer William Herschel discovered a sixth and sev-
enth
satellite
(Mimas and Enceladus). He
rotation of Saturn
by following spots on
Saturn rotated in
10%
hours and that
pendicular to the plane of the rings. circle
Saturn along the line of
its
its
its
also
surface.
studied
He
axis of rotation
The The
the
found that
was
per-
rings, in other words,
equator.
inner satellites also
revolve exactly in the plane of Saturn's equator.
The
rings cast a
shadow on the planet they
to suppose they are solid
and continuous.
A
circle so it
is
easy
strong point in favor
came with the work of the American astronomer William Cranch Bond. In 1848, Bond detected an eighth satellite of Saturn (Hyperion). He made the discovery on September 16; the English as-
of an alternate possibility, however,
tronomer, William Lassell, independently 18.
Two
days
is
Next, in 1849,
two days— Bond
Bond and
made
it
on September
gets the credit.
his son,
George Philips Bond, observed
that the rings of Saturn extended closer to the planet than had
LITTLE FOUND SATELLITE
71
been reported. There was an innermost ring that was dimmer than the
their report
C)
So much
The
certainly couldn't
on November
on December that, too,
and through which
rest
part (Ring
3
and
lost
stars
could be seen. That
be continuous. The Bonds made
15. Lassell
made an independent
report
out again, poor fellow. (See Figure
for observation.
pointed to rings
There was theory,
made up
in addition,
7.)
and
of discontinuous particles.
rings spread out widely in space
and were under the
Figure 7 Saturn as Seen from Above
influ-
One Pole CASSINI'S DIVISION
ence of a gravitational
field
The innermost boundary
that varied in intensity with distance.
of the ring system
is
only 44,000 miles
THE SOLAR SYSTEM AND BACK
72
from Saturn's center (and only 7000 miles above Saturn's surface), while the outermost boundary
86,000 miles from the center
is
of the planet.
We
know
Newton worked
Saturn's mass.
from the distance of
its satellites
and
out
it
first
1687
in
their period of revolution,
using his law of universal gravitation, and his figure has had to
be corrected only
slightly since.
Saturn has 95 times the mass of easily that the gravi-
Earth and from that we can calculate quite
boundary of the
tational intensity at the innermost
and
at the outermost
boundary
0.2
tensity at the surface of the Earth
is
rings
is
0.8
(where the gravitational
in-
taken as 1.0).
In other words, the outermost regions of the ring are under only a quarter the gravitational intensity of the innermost
re-
gions. This gives rise to a strong tidal effect that puts a strain
on
the rings inward and outward.
Then,
most
too,
under the lash of the gravitational
sections should
in their revolution
should
move
move
at a velocity of
12%
force, the inner-
miles per second
about Saturn, while the outermost sections
at 10 miles per second. If the rings
were
solid,
they
would have to move in one piece with the innermost sections going more slowly than the outermost. This would put a tremendous sideways strain on the system. In 1857, the Scottish mathematician James Clerk Maxwell a thoroughgoing analysis of the gravitational situation
that the rings could not stand the strain
uously solid unless they were
They had
many
if
made
and showed
they were contin-
times as rigid as the best
steel.
to consist of separate fragments so thickly strewn as
to appear continuous
when viewed from the
distance of Earth
(not so thickly strewn in Ring C).
This has been borne out amply since.
James Edward tions
The American astronomer
showed by spectroscopic observathat the inner portion of the rings did move more quickly Keeler, in 1895,
than the outer.
As
know how
we
still
don't
telescopes improved
and
as the rings
Despite everything, though, rings are.
still
thick the
remained
LITTLE FOUND SATELLITE invisible
when
several
At
first,
hundred miles
thick, then less
maximum
seen edge-on, the estimates of
ness decreased.
was
it
they had to be
felt
then
thick,
less
than ten miles thick.
73
must be measured in yards some estimates to the effect that they
than
than several dozen miles
Now
thickness
thick-
less
it is
generally felt their
at the most.
I
have seen
are only a foot thick.
The size of the individual particles in the ring is also not known. The thinner the rings, the smaller the particles might be expected to be. They may be no larger than so much gravel. From the efficiency with which they reflect light and from their infrared spectra, it
seems the gravel may be coated with
ice,
or even be mainly
ice.
But why should Saturn have
rings at all?
No
other planets
have them. Well, in 1849, before Maxwell's definitive analysis, a French astronomer, E. Roche, that
when
a satellite
tidal forces will
made and
more general approach and showed primary are of the same density,
a
its
break up the
satellite if it
is
closer to the planet's
center than 2.44 times the planet's radius. This
is
called Roche's
limit.*
There are
six
planets
known
to have satellites. If
we omit
Sat-
urn, here are the figures for the distance of Roche's limit for each
planet and the distance of
its
nearest satellite:
Table Planet
11
Roche's Limit miles
Nearest Satellite
radii
miles
radii
Earth
9,750
2.44
238,500
Mars
5,150
2.44
5,800
2.74
Jupiter
105,000
2.44
110,000
2.56
Uranus
37,000
2.44
77,000
Neptune
35,500
2.44
220,000
60.0
5.17 15.1
* Actually, Roche calculated it on the assumption the satellite is fluid and has no tensile strength. Actual solid satellites can withstand tidal forces better than that and if a satellite is small enough it can remain unbroken even quite close to a planet.
THE SOLAR SYSTEM AND BACK
74
For every one of these planets, the
system
satellite
outside
is
Roche's limit although, in the case of Mars and Jupiter, the
nermost
For Saturn, the distance of Roche's limit
most known is
satellite, as
is
88,500.
The
inner-
December, 1967, was Mimas, which
of
120,000 miles from Saturn's center (3.44 radii). Saturn's
lite
in-
satellite is interestingly close to that limit.
system
is
The outermost edge
of the rings
is,
on the other hand, 86,000
miles from Saturn's center, or 2.38 radii. therefore,
The
inside Roche's limit. Either
is
satel-
also safe.
it
entire ring system,
represents a satellite
which somehow managed to get too close to Satum and which broke up, or
represents part of the original cloud of matter
it
about Saturn which was too close to Saturn for allow If
it
to coalesce into a satellite in the
the rings are a disintegrated
rather large one.
mass of the inal satellite
I
satellite,
tidal effects to
place.
first it
may have been
have seen one estimate which placed the
Moon.
rings at one-quarter that of the
would have had
If so,
a
total
the orig-
to have a diameter of about 1300
miles.
And what about the division (which
Cassini's division? If there is
were
particles in
about 2500 miles wide, by the way), they
would revolve about Saturn
in 11 hours.
However, Mimas revolves
and Tethys in 45 hours. would be pulled by Mimas from the same direction every two of the particle's revolutions, by Enceladus every three, and by Tethys every four. The same pull from in 22 hours, Enceladus in 33 hours,
A particle
in Cassini's division
the same direction would permanently slow closer to Saturn, or speed
until the
new
distance
is
it
up and
force
it
it
down and
farther
force
such that the synchronization
stroyed. In this way, Cassini's gap
is
swept clear of
it
from Saturn is
de-
particles.
Other gaps are likewise swept by synchronization with the nearer satellites, but nowhere is the sweeping as multiple and as efficient as in Cassini's division.
But now
let's
consider Saturn's
satellites.
In 1898, the Amer-
LITTLE FOUND SATELLITE ican astronomer
ninth
urn's
75
William Henry Pickering discovered Phoebe,
satellite,
and
nothing new was added.
The
Sat-
almost seventy years after that,
for
list
of
satellites,
from Saturn out-
Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion, Iapetus, and Phoebe. It almost seemed as if that were
ward,
was:
going to be permanent.
To
be
named
sure, Pickering reported a tenth satellite in
it
He
Themis.
reported
from Saturn, which placed
Two
satellites so
spaced.
Of
1905 and
at a distance of 908,000 miles
at nearly the orbit of Hyperion.
near the primary are not likely to be so closely
course,
Themis was reported
and a rather high
of 39
it
it
to
have a high inclination
eccentricity as well, so that
it
wasn't likely
However, a high inclination and
to collide with Hyperion.
ec-
centricity for a satellite that close to Saturn are also unlikely. It
a suspicious satellite all
is
that
around and
Themis was never seen
taken, that's
A
it is
again. Pickering
not at
all
surprising
must have been mis-
all.
close study of faint divisions in Saturn's rings, however, in-
dicated that additional satellites, very close to Saturn, might exist. If so,
be
they would be so close to the outer edge of the rings as to
lost in their glare.
Then,
December, 1967, something
in
dra-
matic happened. This was a time when Saturn's rings showed edge-on and disappeared, and such a once-in-fifteen-year opportunity can
be important. With the
rings out of sight, objects in the
near vicinity of the rings might be seen. In that December, a French astronomer, Audouin Doll f us,
lo-
cated a tenth satellite of Saturn, closer to the planet than Mimas, even.
The
little
found
satellite
proved to be 98,000 miles from
the planet's center (2.73 radii), which puts
than Mimas, but
still
it
22,000 miles closer
10,000 safe miles outside Roche's limit
and 12,000 miles beyond the outer edge of the satellite revolves
Dollfus
named
it
Janus after a
Roman god who
The new
is
pictured with
and one backward. Janus is beginnings and endings, of arrivals and departures, of
a double face, one looking forward
the god of
rings.
about Saturn in 18 hours.
THE SOLAR SYSTEM AND BACK
j6 entrances and
of doors in
exits,
and doors out (which
is
why
the
guardian of the doors, and, eventually, of the house generally, called a "janitor"). In this case, the
discovered and the so
it is
the largest
how
is
satellite
new
satellite is
the
be
last to
reading from Saturn outward,
estimated at 300 miles, which would
would
make
it
discovered in over a hundred years. Consider-
surely
you can
have been discovered long ago
if it
see
hadn't
for the rings.
Janus's invisibility
seeming to swallow it
list
telescopes have improved in that interval,
that Janus
been
on the
"Janus."
Janus's diameter
ing
first
is
disgorge.
is
its
another case of Saturn (and of children. Dollfus
its
rings)
was the Zeus that made
6
VIEW FROM AMALTHEA
months ago
Several
2001:
A
ment
I
I
attended a preview of the motion picture
Space Odyssey here
in Boston. Against
my
better judg-
even got into a tuxedo for the occasion.
Perhaps the tuxedo contributed to an unwitting bit of pomposity
my
on
irrational
part,
for at
one point
I
dissolved into a
semi-
spasm of anger.
see, I have included in a number of my stories something "The Three Laws of Robotics," of which the first is: "A robot may not harm a human being or, by inaction, allow a human being to come to harm." The laws are a purely fictional device, but they had been picked up by other writers, who take them for granted in their robot stories, and over the years I have come to take them very seriously indeed.
You
I call
In 20oi the most dramatic episodes involve an intelligent comf
my
puter (equivalent to one of
about the death of several
robots)
human
happen was made abundantly
beings.
who
the aisle toward a friend of mine
Law! They're breaking
I
First
this
was going to
clear to the audience just before the
mid-point intermission, and at intermission
In tones of deep shock,
deliberately brings
That
I
said to
Law!"
I
went seething up
noticed in the audience.
him, "They're breaking First
THE SOLAR SYSTEM AND BACK
78
And my
friend answered, calmly, "So
why
them
don't you strike
with lightning, Isaac!"
Somehow
my
that restored
perspective
and
watched the
I
rest
of the picture with something like calm and was even able to enjoy
an arousal of
curiosity.
Near the end of the picture when the spaceship was approaching Jupiter, several satellites were visible as small globes near the giant globe of the planet
itself.
at once, trying to figure out
them
all in
I
started counting the satellites
whether
it
was
really possible to see
the sizes indicated from any one point in space.
Unfortunately, because they kept changing scenes, and because I
could not remember the necessary data exactly enough or manip-
ulate
them without trigonometric
tables,
I
could
come
to
no
conclusion.
So
let's
To
you and
I
work
out together now,
it
begin with, Jupiter has twelve
known
if
we
can.
of which
satellites,
four are giants with diameters in the thousands of miles, and the
other eight are dwarfs with diameters of a hundred
fifty
miles or
less.
Naturally,
want
we want
if
to choose
giants. If
we
do, then seven of the eight dwarfs are
millions of miles
than
we would
to see a spectacular display,
an observation post reasonably close to the four
away and would not be seen
as
bound
to
be
anything more
starlike points of light at best.
Let's ignore the dwarfs then.
There may be some
following a starlike object that shifts stars,
but that
is
not at
all
its
position
comparable to a
interest in
among
the other
satellite that
shows a
visible disk.
Concentrating on the four giant that or
we
more
satellites,
we
will surely agree
don't want to take up an observation post from which one
much of its time in the direcwe would be forced to watch it defy anyone to pay much attention
of the satellites will spend
tion of Jupiter. If that happens,
with Jupiter in the sky, and
I
VIEW FROM AMALTHEA to
any
when
satellite
there
is
79
a close-up view of Jupiter in the field
of vision.
For that reason, we would want our observation post in a
posi-
tion closer to Jupiter than are the orbits of any of the four giant
Then we can watch
satellites.
all
them with our back
four of
to
Jupiter.
We
could build a space station designed to circle Jupiter at
and always watch from the side away from Jupiter, but bother? There is a perfect natural station with just the prop-
close range
why
erties
we
need.
It is Jupiter's
The
innermost
any of the
closer to the planet than
satellite, a
four giant satellites of Jupiter were the
discovered anywhere in the solar system
Moon, 1610,
dwarf that
first satellites
(except for our
to
Galileo,
be
own
Three of them were discovered on January and he spotted the fourth on January 13.
of course).
by
is
giants.
7,
Those remained the only four known satellites of Jupiter for And then, on September 9, 1892, the American astronomer Edward Emerson Barnard detected a fifth one, much dimmer and therefore smaller than the giant four, and nearly three hundred years.
also considerably closer to Jupiter.
The cal
discovery
came
as
somewhat of
having four ently, that
proper
satellites
and no more. The shock was
of
its
own. They called
Jupiter's satellites to
come
so great, appar-
astronomers could not bear to give the newcomer a
name
the discoverer, and also "Jupiter
has
a shock, for the astronomi-
world had grown very accustomed to thinking of Jupiter as
to
V"
it
"Barnard's Satellite" after
because
be called Amalthea,
after the
was the
it
be discovered. In recent
years,
nymph
fifth
however,
(or goat)
of it
who
served as wet-nurse for the infant Zeus (Jupiter).
Amalthea's exact diameter
is
uncertain (as
every satellite in the solar system but the figure given
is
is
Moon
the diameter of
itself).
100 miles with a question mark after
it. I
The
usual
have seen
estimates as large as 150 miles. For our purposes, fortunately, the
exact size doesn't matter.
THE SOLAR SYSTEM AND BACK
80
There
is
no
direct evidence,
but
it
seems reasonable to suppose
that Amalthea revolves about Jupiter with one face turned eternally toward the planet. Jupiter's mid-point
is
edge of that "sub-Jovian"
The
horizon.
When
the center of Jupiter
side,
satellite,
standing on the very
planet (as seen from Amalthea)
isphere before
Jupiter
half the surface of the
is
is
right
on the how-
so huge,
one must go a considerable distance into the other hem-
ever, that
From
On
always visible.
all
of Jupiter sinks below the horizon.
roughly one-quarter of the surface of Amalthea, eternally
is
of
all
below the horizon and the night sky can be
contemplated in peace and quiet. For our purposes, since we want
we
to study the satellites of Jupiter,
will
take a position
(in
imagination) at the very center of this "contra-Jovian" side of
Amalthea.
One
object that will be visible in the contra-Jovian
Amalthea, every so often,
n
Jupiter in
will
be the Sun. Amalthea revolves about
hours and 50 minutes. That
too, with respect to the stars
is its
sky in 11 hours
will
period of rotation,
and (with a correction too small to
worry about) with respect to the Sun as well.
Amalthea, the Sun
sky of
make
appear to
To an
observer on
a complete circle of the
and 50 minutes.
Since Amalthea revolves about Jupiter directly, or counterclock-
Sun
wise, the
and there
With
am
will
appear to
will
be
5
rise in
the east and set in the west,
hours and 55 minutes from sunrise to sunset.
this statement,
which
I
introduce only to assure you
not unaware of the existence of the Sun,
matter of
satellites exclusively for
Sun has something I will
take
The
up
to
will pass
on
I
to the
the remainder of the essay.
The
do with them, but what that something
is,
in the next chapter.
four giant satellites, reading outward from Jupiter, are: Io,
Europa, Ganymede, and Jupiter
I
I,
Jupiter
II,
in abbreviated form,
Callisto.
J-I, J-II,
Sometimes they are
and Jupiter IV J-III, and J-IV.
Jupiter III,
called
respectively or,
VIEW FROM AMALTHEA
what we want, the abbreviations are very conven-
Actually, for
The names
ient.
mind which
we go
centrate
are irrelevant after
nearer and which
is
With
by.
all,
and
farther
is
and
difficult to
it is
that's
what we need
to
keep in
those names are
if
we can
the abbreviations, on the other hand,
on the order of distances of the
vious way,
8l
all
con-
satellites in a very ob-
make the
data in this article
meaningful.
Using the same system,
can and, on occasion,
I
will
call
Amalthea J-V. Generally, though, since it is to be our observation point and therefore a very special place, I will use its name. So
let's start
satellites
with the basic
statistics
Table 12), with those
(see
good measure. Of the data
for
for Callisto as high as
you in
is
Amalthea 12,
For instance, can
I
tell
little
have seen
I
What
I
figures
have given
from the various sources
library.
For comparison, the diameter of our own so that
also included
the least satisfactory
3220 and as low as 2900.
the consensus, as far as
my
Table
in
are the values for the diameters.
concerning the four giant
for
we can
thinner,
say that
and
J-III
J-I is
a
little
Moon
2160 miles,
is
wider than our Moon,
J-II
a
and J-IV considerably wider.
In terms of volume, the disparity in size between
on the one hand, and our Moon, on the other, the two largest Jovian satellites
is
3.3
is
J-III
and J-IV, Each of
larger.
times as voluminous as the
Moon. However, they are apparently less dense than the Moon (perhaps there is more ice mixed with the rocks and less metal) so that they are not proportionately more massive. Nevertheless, J-III
massive as the
Moon;
is
massive enough.
it is
It is
not only twice as
the most massive satellite in the solar
system. For the record, here are the figures on mass for the seven giant satellites of the solar system (see Table 13).
cludes not only the four Jovian giants and our
can
call E-I),
therefore N-I, will
but Triton, which
and Titan, which
be made clear
later.
is I
The
Moon
Neptune's inner
will call
S-VI
table in-
(which
satellite
we and
for reasons that
THE SOLAR SYSTEM AND BACK
82 If
we
are going to view the satellites, not from Jupiter's center
(the point of reference for the figures on distance given in Table
Table 12-The Five Inner Jovian Satellites
Name
Satellite
Diameter (miles)
Distance from
Center
Jupiter's
(miles)
J-v
Amalthea
J-I
Io
100
113,000
2,300
262,000 417,000
J-II
Europa
i,95o
J-III
Ganymede
3,200
666,000
J-IV
Callisto
3,200
1,170,000
Table 13-Masses of Satellites
Name
Satellite
Mass (Moon =
J-III
Ganymede
2.1
S-VI N-I
Titan
19
Triton
i-9
J-IV
Callisto
i-3
EI
Moon
1.0
JI
Io
1.0
J-II
Europa
0.65
12) but from the observation post
1.0)
on the contra-Jovian surface of
Amalthea, then we have to take some complications into account.
When
any of the
satellites, say J-I, is directly
contra-Jovian point,
it
and Amalthea form a
above Amalthea's straight line with
Jupiter. J-Fs distance
from Amalthea
from
minus the distance of Amalthea from
Jupiter's center
ter's center.
This represents the
is
then equal to
minimum
its
distance of
distance
J-I
Jupi-
from
Amalthea.
As
J-I
draws away from
from the observation point
when
it is
this
overhead position,
increases,
and
is
its
distance
considerably higher
on the horizon. The distance continues
to increase as
VIEW FROM AMALTHEA it
sinks
below the horizon until
83
reaches a point exactly
it
opposite side of Jupiter from Amalthea.
The
entire
on the
width of
Amalthea's orbit would have to be added to the distance between
Amalthea and
Of
J-I.
from our vantage point on Amalthea's surface, we would only be able to follow the other satellites to the horizon. course,
We will be faced with a mum
minimum
distance at either horizon.
details,
I
distance at zenith and a maxi-
Without
will present those distances in
troubling you with the
Table
14.
Table 14-Distances of the Jovian Satellites from Amalthea Distance from Amalthea (miles)
Satellite
At zenith
At horizon
J-I
149,000
236,000
J-II
304,000
403,000
J-III
553,000
659,000
J-IV
1,057,000
1,168,000
This change in distance from zenith to horizon peculiar to Jupiter's satellites. It
observation
Moon
is
is
is
not something
true whenever the point of
not at the center of the
orbit.
The
distance of the
from a given point on the surface of the Earth
is
greater
when the Moon is at the horizon than when it is at the zenith. The average distance of the center of the Moon from a point on Earth's surface is 234,400 miles when the Moon is at zenith and 238,400 when it is at the horizon. This difference is very small because
it is
When
the
only the 4000-mile radius of the Earth that
Moon
is
is
involved.
we must look at it across half which we need not do when it is at the
at the horizon,
the thickness of the Earth, zenith.
From
a point
on Amalthea's
surface, however,
we must
across a considerable part of the 113,000-mile radius of
which makes more of In the case of our
look
its orbit,
a difference.
Moon, we
are dealing with an orbit that
is
THE SOLAR SYSTEM AND BACK
84
markedly
elliptical so that
one point
in its orbit
and
it
can be as close as 221,500 miles at
as far as 252,700 at another point. For-
tunately for myself and this discussion, the orbits of the five
Jovian satellites
and
we
ellipticity is a
are discussing are all almost perfectly circular
complication
Given the distance of each diameter of each
don't have to face here.
satellite
satellite, it is
size of each, as seen
we
from Amalthea, and the
possible to calculate the apparent
from our Amalthean viewpoint (see Table
15).
Table 15-Apparent Size of Jovian Satellites as Seen from Amalthea Diameter (minutes of arc)
Satellite
At zenith
At horizon
J-II
53 23
34 17
J-III
20
17
J-IV
10
9
J-I
If
you want to compare
this
with something familiar, consider
that the average apparent diameter of the
This means that
J-I,
for instance,
is
Moon
is
just slightly larger
Moon when it rises, bloats out to a circle half again as Moon when it reaches zenith, and shrinks back to size
when
it
sets.
The
other three
31' of arc.
satellites,
than the
wide its
as the
original
being farther from
Amalthea, do not show such large percentage differences in distance from horizon to zenith
and therefore do not show such
differences in apparent size either.
Notice that although
J-III is
also considerably larger.
from Amalthea so that from the other
considerably farther than
The two
J-II
and
effects
J-III
counterbalance as seen
appear indistinguishable one
in size, at least at the horizon.
closer, bloats just a little
more when
J-II, it is
it
Of
course, J-II, being
reaches zenith.
As
for J-IV,
VIEW FROM AMALTHEA smallest in appearance,
it is
diameter of our
The
85
and shows only one-third the apparent
Moon.
sky of Amalthea puts on quite a display, then. There are
four satellites with visible disks, of which one
But never mind
satellite,
Sun, and (its
considerably
what about brightness? Here
size;
factors are involved. First there
each
is
Moon.
larger than our
is
several
the apparent surface area of
then the amount of light received by
from the
it
by
finally the fraction of received sunlight reflected
albedo). In Table 16,
I list
it
each of these bits of data for each
of the four satellites, using the value for our
own Moon
as basis
for comparison.
Table 16-The Jovian Satellites and Our Moon atellite
Apparent Area
Sunlight
(Moon =:i.0)
Received
Maximum Minimum (Moon=
Albedo
(Moon =
H
2.92
1.20
0.037
j-ii
0.55
0.30
0.037
5-5
j-iii
0.42
0.30
0.037
3
J-IV
0.10
O.O84
0.037
0.4
If
we
consider the figures in Table 16,
from Amalthea
is
ceives,
however
that received by the after
Sun
all,
as
is
at
it is
Moon. This
J-I
as seen
up
is
of sunlight
satellites),
not surprising.
is
it re-
only
%
The Moon,
an average distance of 93,000,000 miles from the
compared
The Moon
see that
At zenith it our Moon. The intensity
do the other Jovian
(as
we
5
will possess an area
remarkable.
to three times that of
1.0)
1.0)
to 483,000,000 miles for the Jovian satellites.
has no atmosphere and therefore no clouds— and
atmospheric clouds that contribute most to light reflection.
The Moon,
therefore,
the light
receives
it
showing bare rock,
reflects
only about
from the Sun, absorbing the
rest.
%4
of
THE SOLAR SYSTEM AND BACK
86
The Moon's mark
is
%
bettered by
and
J-II,
J-I,
which
In fact,
J-III.
J-II reflects
about
good
Earth can manage. This doesn't necessarily mean that
as the
of the light
these three satellites have an
Earth.
seems more
It
it
receives,
is
every bit as
atmosphere and clouds
like
the
likely that there are drifts of water-ice
and
ammonia-ice (or both) on the surfaces of the
satellites,
and that
these drifts do the reflecting. Callisto, for
and
some
reason, reflects only
%
oi the light
composed
is
that astronomers have badly overestimated (If
it
Or
of particularly dark rock.
were smaller than astronomers think
is it
conceivable
Callisto's
it is,
receives
Moon. Perhaps
therefore less than half as reflective as the
is
Callisto
it
it
diameter?
would have
to
more light to account for its brightness.) Anyway, we can now calculate the apparent brightness of each
reflect
satellite
(as
compared with our Moon) by multiplying the area
by the amount of sunlight received by the albedo. The
results are
given in Table 17.
Table 17-Apparent Brightness of the Jovian Satellites Apparent Brightness (Moon
Satellite
= i.o)
Maximum Minimum
As you thea, can
J-I
0.54
0.22
J-II
0.11
0.06
J-III
0.045
0.033
J-IV
0.0015
0.0012
see,
not one of the Jovian
compare
from the Earth's
in
tieth;
J-II
is
less
and J-IV
And
yet
who
is
Even
J-I,
Moon
as seen
the closest to Amalthea and
never better than half as bright as the
than a seventh
less
seen from Amal-
apparent brightness with our
surface.
therefore the brightest,
Moon;
satellites, as
as bright; J-III less
than a twen-
than a six-hundredth.
says brightness
is
everything?
only %65>ooo as bright as the Sun, and alone, it is all the better for that.
if
Our own Moon is we consider beauty
VIEW FROM AMALTHEA Perhaps the Jovian
more
seen from Amalthea will be
Moon,
beautiful than our
It will result,
will
satellites as
87 still
for being so softly illuminated.
perhaps, in better contrast, so that craters and maria
be more clearly
visible. If
the
satellites are partly ice-covered,
patches of comparative brilliance will stand out against the darkness of bare rock. It will be
all
the more startling because on Amal-
thea there will be no air to soften or blur the sharpness of the view.
may be most
Callisto
beautiful of
field glass to see it at its best. It
mysteriously low albedo. Perhaps
its
lump
of coal, with
ice so interspersed
diamonds
its
There are only two
it
may
might look rather
than a solid
it
will
seem
a cluster of
ten.
Uranus
is
so
in a way.
Whereas no
less
it still
tackle
for Jupiter.
From
and
puts on a bet-
than seven of Jupiter's twelve
small and distant they can be ignored,
Saturn's need be neglected.
let's
satellites to Jupiter's twelve,
only one giant as compared to Jupiter's four,
show
real
a special problem
briefly in
Although Saturn has only ten
ter
have
opposed to merely one or two. These are
and Saturn with
Chapter 3), but Saturn according to the system we have already used
are
with
like a
circle of light.
planets, other than Jupiter, that
mentioned
(for reasons I
require a
satellite,
very occasional patches of highly-reflecting
families of satellites, as five
it
by very dark rock that
in the sky, rather
Uranus with
though
all,
would be a darkling
only three of
Saturn's innermost satellite, six
other satellites can be seen with visible disks, and not four only. Let's satellites
start
(see
by giving the basic
The Roman numerals for Jupiter satellites
for
statistics
Saturnian
the
Table 18).
but
I
are not as well established for Saturn as
have seen them used from
I
through IX for the
from Mimas through Phoebe. Janus was discovered
at
won't
re-
the very end of 1967 (see the preceding chapter) but
I
organize the numbering system because of that. Just as Jupiter's closest satellite
is
S-X (even though
J-V, so it
I
will let Saturn's closest satellite
looks like a prudish
way
be
of writing "sex").
.
the solar system and back
88
Table 18-The Saturnian Satellites
Name
Satellite
Diameter
Distance from Saturn's Center (miles)
(miles)
S-X
Janus
300
98,000
SI
Mimas
320
115,000
S-II
Enceladus Tethys
370 800
149,000
Dione Rhea
800
234,500
1,100
328,000
S-VI S-VII
Titan
3,100
760,000
Hyperion
250
922,000
S-VIII
Iapetus
2,213,000
S-IX
Phoebe
750 190
S-III
S-IV
s-v
Besides,
if
we
8,043,000
place our observation point on Janus (or S-X)
will
be convenient to number the
and
so on.
we assume
If
183,000
satellites in its
sky as
S-I, S-II,
that Janus presents one face, always, to Saturn
and take up our position
at the contra-Saturnian position,
never see Saturn and
rings
on the
We
nian
its
and we
will
we
will
be able to concentrate
satellites.
can work out the zenith and horizon distances of each
satellite
system,
it
from Janus,
as
we
did in connection with the Jovian
and from that determine the apparent
satellites (see
As you
see,
most three
sizes of
the Satur-
Table 19).
the situation on Janus
is
most amazing. The
are only starlike points
satellites
omitted from the table.
The
other
six
outer-
and are therefore
satellites,
which are
in-
cluded, are so closely spaced and increase in size so steadily as one
goes outward that
the same
our
size.
own Moon
all
appear, on the horizon, to be very
much
All have an apparent diameter about half that of (S-I
a little smaller, while
and
S-III are a little larger, S-II
S-IV and S-VI are
This picture of sextuplet
satellites
and S-V
are
just right) is
quite unique. Nothing
view from amalthea Table 19-Apparent
from Janus
as Seen
Diameter (minutes of arc) Zenith Horizon
Satellite
like it
89
Size of Saturnian Satellites
SI
65
S-II
25
11
S-III
32
18
S-IV S-V S-VI
20
15
17 16
13
18
15
can be seen from any other point in the solar system, not
even from any other point in the Saturnian system.
Each effect
of the six satellites bloats as
approaches the zenith, the
it
being more extreme the closer the
from a diameter half that of the
Moon
of the
Moon
at zenith. Its area
satellite.
S-I
expands
at the horizon to twice that
(and therefore
any given phase) increases thirteen-fold, as
it
its
brightness at
travels
from horizon
to zenith.
And
the brightness of the Saturnian satellites? Here there
difficulty that
for there are
turnian
was not present
no
We
I
However,
S-I
can find on the albedos of the Sa-
and
S-II are
thought to be largely
is
the solar system
albedo of the Saturnian
satellites 0.5, or
seven times that of the
Moon. Working with
that assumption and realizing that the
delivers only 0.011 as
much
our
own Moon, we can
Saturnian
satellites as
about as bright
Sun
light to the Saturnian satellites as to
calculate the apparent brightnesses of the
seen from Janus (see Table 20).
Here we have a picture of ellites,
a
known to have an atmosphere (the only satelknown to have one). won't be too far out then if we decide to make the general
snow and S-VI lite in
figures that
satellites.
is
in the case of the Jovian satellites,
a soft
and
as Callisto (the
delicate family of
dimmest
dim
sat-
of Jupiter's four
giant satellites), as seen from Amalthea. All are only
%
o to
%
o
THE SOLAR SYSTEM AND BACK
90
Moon. Only one
as bright as the
to shoot
Does Jupiter
So
of the Saturnians, SI,
up to the unusual mark of
%
as bright as the
this give us all we need to know about the and Saturn? Heavens, no!
far
I
have painted only a
and
static picture
fascinating aspects of the situation untouched. lites
of Jupiter as seen from Amalthea,
manages
Moon.
satellites of
left
the most
Those four
and those
satel-
six satellites
of
Saturn as seen from Janus, are moving relative to each other. Each
moves
at
its
own
characteristic rate
and the group forms an
ever-
changing pattern.
What's more, the Sun moves mentioned
briefly
across the sky, too (something I
near the beginning of the chapter) and that
introduces interesting complications, too, such as phase-changes
and I
eclipses.
will try to
work out the motion picture of the Jovian
lites, at least, in
satel-
the next chapter.
Table 20-Apparent Brightness of Saturnian Satellites Satellite
Brightness
(Moon =
Zenith
Horizon 0.0032
S-I
0.0115
S-II
0.0042
0.0020
S-III
0.0057
0.0032
S-IV
0.0035
0.0027
S-V
0.0030
0.0023
S-VI
0.0028
0.0027
1.0)
THE DANCE OF THE SATELLITES
People always seem to be amazed over the fact that
I
am
forever
writing about spaceships but never get into an airplane; that
my
have
characters travel
all
over the galaxy while
I
I
myself drive
to a neighboring state only with the greatest reluctance.
"You don't know what
And to
they're right,
be said
you're missing/' they keep saying.
suppose, except that there's something also
I
thought alone.
for traveling in
three-dimensional as the real thing, but
For instance, about
and the
Falls,
trip
borhood of the cinated;
it
We got a
Falls,
I I
Falls
had
and
my
was so pleased
lay
down
pulled into the neigh-
I
it
was!
I
was
fas-
had nerved myself
at last, so that
My eyes closed,
a train that neither
was.
I
clear
dull roar that filled the
it
We
to
I
might sink
so richly earned.
tried to.
frown rested on
where
drove the family to Niagara
I
turned a corner, and there I
quite as
nice pair of rooms in a motel in the very near neigh-
into the rest
was
may not be
saves trouble.
trip.
borhood of the at least
ago
wasn't bad at that.
was majestic;
the 400-mile
Or
five years
It
it
then opened, and a puzzled
and ingenuous forehead. There was a
room
like a
nearby train except that
it
approached nor receded, but remained
THE SOLAR SYSTEM AND BACK
92
After a while,
identified the sound.
I
With
great indignation
I
realized that they did not turn the Falls off at night.
There you have
it.
An
sive as the real thing,
imagined Niagara
but
may not be
quieter.
it is
never see the view from Amalthea which
I shall
the previous chapter— not even
if
tem were
moment
available at this very
as impres-
described in
I
a rocket ship to the Jovian sys-
with tickets for sale at a
and one of them reserved in my name. Still, I can imagine the view, and do so, gratis, in the peace and quiet of dollar a passenger
my
attic.
While I'm
at
it,
then,
satellites of Jupiter as
will
I
now go on
moving
to consider the five inner
bodies, rather than as static ones.
All revolve about Jupiter in fixed periods.
The
closer to Jupiter,
the faster a satellite moves relative to the planet and the smaller its
orbit about
We
it;
and, for both reasons,
its
period
is
shorter.
can begin then by considering the period of revolution of
each of the
satellites
comparable,
we can
and, in order to give
them
all in
make
those periods directly
hours (see Table 21).
In traveling a circular path about Jupiter, each satellite sweeps (since every circle, whatever
over 360
360
By
).
Table
its size,
can be divided into
dividing the period, in hours, into 360
we
,
find
21 -Motion of Jovian Satellites Relative to Jupiter
Name
itellite
Period
Motion per Hour
(hours)
(degrees of arc)
J-V
Amalthea
11.83
J-I
Io
42.45
J-II
Europa
86.22
J-III
Ganymede
171.7
J-IV
Callisto
400.5
+30.43
+ + + +
8.50 4.18 2.10
0.90
many
degrees of arc each satellite traverses in one hour.
figure
is
The
how
given in the last
column
That
of Table 21.
degrees of arc traversed in an hour are given as positive
THE DANCE OF THE SATELLITES figures,
because the
moving
satellites are
in
direct,
Chapter 3). Suppose we imagine ourselves somewhere above
93 or counter-
clockwise, rotation (see
tor, well
above
can observe the
its
Jupiter's equa-
unimaginably stormy atmosphere, so that we comfort. Suppose, also, that
satellites in
motionless with respect to Jupiter's center, which means
not partake in Jupiter's rotation. All the
satellites
we are we do
would then be
seen to rise in the west, travel across the sky, pass overhead, then sink in the east.
But suppose we
ourselves, while observing,
iter in
the same counterclockwise direction.
slowly,
we would
seem
partially overtake
to us, then, to
move more
the west and set in the
and
east,
the
slowly.
were to
circle Jup-
Even
we
satellites
if
did so
which would
They would
rise in
still
but would take longer between
rising
setting.
we speeded our own motion more and more, the satellites would seem to move more and more slowly, as observed by ourselves from our moving vantage point. Finally, if we circled JupIf
iter at a
speed that swept out +0.90 ° per hour,
even with Callisto.
The
east,
motionless in the sky as
we matched
could
still tell
stay
rise in
but Callisto would seem to remain
the west and set in the
we
we would
other satellites would continue to
that Callisto was
it
step for step.
(Of course,
moving by comparing
its
posi-
tion night after night with the neighboring fixed stars, but in this essay
we
are completely ignoring the motion of the satellites
relative to the stars.
system
Our view
is
confined entirely to the Jovian
itself.)
If we continued to hasten our motion, we would more than match Callisto— we would outrace it and it would seem to fall behind. It would rise in the east and set in the west and would seem thus to travel in a direction opposite to that of its real mo-
tion relative to Jupiter.
(No
mystery!
If
two
trains
were racing in
the same direction on parallel tracks, passengers on the faster train
would
see the slower train
overtaken, even though
it is
seem to move backward
really
moving forward.)
as
it
is
THE SOLAR SYSTEM AND BACK
94
As our own personal speed increased, we would next overtake Ganymede and force that into apparent east-to-west motion, then Europa, then
But
Io,
and
so on.
not set ourselves an arbitrary motion. Let us place our-
let's
selves
on Amalthea, J-V, where we were
That
will give us a fixed
interested in a
more
about Jupiter
something
is
Jupiter's center,
and
in the preceding chapter.
speed of +30.43 ° per hour. (If you're figure,
Amalthea's speed
like 16.7 miles per
second relative to
easily
this
is
visualized
nearly equal to the 18.5 miles-per-
second figure of Earth's motion about the Sun. Compare this
with Callisto, which moves at a speed of only
5.1
miles per second
relative to Jupiter's center.)
Amalthea sweeps out many more degrees any other of takes
them
and so
Jupiter's satellites, of course,
all.
of Amalthea,
From
all
in the west. (I
it
time than
handily over-
our vantage point on the contra-Jovian side
the giant satellites would
am
in a given
rise in
the east and set
assuming, here, that Amalthea turns one face
eternally toward Jupiter.)
We
can easily determine the rapidity of this motion relative to
Amalthea by subtracting the degrees-per-hour motion of Amalthea relative to Jupiter from the corresponding value for each of
the other four
hour
satellites.
relative to Jupiter
Thus,
and
to Jupiter, then Callisto
if
Amalthea moves +30.43 ° per
Callisto
moves +0.90 per hour
relative
— 29.53
—
moves (+0.90) (+30.43), or The minus sign here would
per hour relative to Amalthea.
indi-
cate that Callisto, as seen from Amalthea, was traveling east to west.
The motions
of the various satellites as seen from
Amalthea are
given in Table 22. Having presented the names of the satellites in
Table
21,
1
will
henceforward (as
I
did in the previous chapter)
continue to refer to them only by the
Roman
numeral
identi-
fication.
As you west,
see,
the
satellites all
something which
reflects
move
quite rapidly from east to
Amalthea's very rapid motion
the dance of the satellites
95
Table 22-Motion of Jovian Satellites Relative to Amalthea
Motion per Hour
Satellite
(degrees of arc)
-21.93 -26.25
J-I
J-II
J-III
-28.33
J-IV
-29.53
The
from west to
east.
that satellite
moves and the more
after
Amalthea. None of the
course, but
only 22
Amalthea, the
closer a satellite to
effectively
satellites
it
does this very well, of
the closest to Amalthea, manages to
J-I,
faster
tends to chase
per hour, whereas J-IV, the most distant,
fall
behind
falls
behind
29 y2 ° per hour. It
thea, it
would seem then that the more distant
and the more slowly
moves
we
it
in Amalthea's sky.
a satellite
turns about Jupiter, the
This
may sound
from Amal-
more quickly
paradoxical, but
all
more distant and slow a satellite, the more rapidly it is overtaken by Amalthea. Let's put this into more familiar terms. From the motion in are saying
that the
is
degrees per hour,
would take to
it is
through a complete to
Amalthea
not hard to calculate
traverse
(see
360
circle
.
and
This would give
its
how many move the
Table 23-Period of Jovian Satellites Relative to Amalthea Period of Revolution (hours)
J-I
16.4
J-II
13-7
J-III
12.7
J-IV
12.2
it
satellite
period, in hours, relative
Table 23).
Satellite
hours
THE SOLAR SYSTEM AND BACK
96
The rise
period of revolution gives us the time lapse from
Amalthea
satellite-
(Actually, there's a small complication here
to satellite-rise.
somewhat over a hundred thousand miles removed from the center about which the satellites orbit. This means that a given satellite is 226,000 miles farther from Amal-
in that
is
thea at some parts of seen from Amalthea satellite-rise to
its
satellite-set
strictly is
as
uniform and the time from
not quite equal to the time from
We
satellite-set to satellite-rise again.
com-
will dispose of these
by ignoring them.)
plications
It so
motion
orbit than at other parts. Its
not
is
happens that Amalthea and the four giants
all
revolve in
orbits that are nearly exactly in Jupiter's equatorial plane. Callisto's
orbit
(Compare
is
the most tilted but even so
this
about 18
only about
is
own Moon, which
with our
has an
off.
orbit tilted
to the plane of the Earth's equator.)
This means that every time one
Amalthea's
sky, there
Ganymede and
is
an
Callisto to just miss
another in
passes
satellite
(Actually,
eclipse.
it
one another
times, but even for them, a partial eclipse
is
possible for
in passing,
would be the
In order to determine the frequency of eclipses then, necessary to calculate
how
long
would take one
it
take another. It would always be the
would do the overtaking
more
%°
for
it
rapid east- to-west motion.
is
more
some-
rule.) it is
only
satellite to over-
distant satellite that
the more distant that has the
The more
distant satellite
would
approach the nearer (and usually larger-in-appearance) from the east, slip
behind
it,
There would be
The
six
at
its
west.
types of two-satellite eclipses altogether.
period between such eclipses, and the
would take from Table I
and emerge
initial
maximum
time each
contact to final break-free, are given in
24.
leave
it
to
you
to calculate
(if
you wish) the time between
the various possible three-satellite eclipses: I-II-IV, I-III-IV, and II-III-IV.
You might wonder why
I've left
out
I-II-III,
but apparently the
the dance of the satellites Table 24-Satellite-Eclipses
Time between
Eclipse
97
Seen from Amalthea
as
Maximum
Eclipses
Duration of
(hours)
Eclipse (minutes)
J-IV/J-III
300
25.0
J-III/J-II
173 110
20.7
/J-I
83
17.5
J-III/J-I
56
11.7
J-IV/J-I
47
8.2
J
IV /J-II
J-II
three innermost giant satellites,
10.1
J-I, J-II,
and
J-III,
do not move
completely independently in their orbits but maintain a certain fixed relationship that precludes their ever being in a straight line
on the same line
side of Jupiter (although they can
be
in a straight
with two on one side of Jupiter and one on the other).
This eliminates the
what would have been
I-II-III eclipse
a
and
also
(more's the pity)
most remarkable coming together of
all
four satellites in Amalthea's sky.
But now, what about the Sun? Amalthea sume) one
on
its
rotates about Jupiter in side always facing Jupiter.
axis, relative to
11.83 hours, with
That means
it
(we
as-
also rotates
the Sun, in 11.83 hours. (The correction
that needs to be applied as a result of Jupiter's motion in
its
about the Sun in the course of that 11.83-hour period
so small
it
is
orbit
can be ignored.) As seen from Amalthea's contra-Jovian point,
then, the there
is
Sun
rises in
the east at 11.83-hour intervals, so that
a 5.92-hour day
and a 5.92-hour
night.
(The changing
distance of Amalthea from the
Sun in the course of the satellite's revolution about Jupiter is small enough to be neglected.) To a viewer on Amalthea, the Sun would be just 6' of arc in
diameter, a bit less than one-fifth Earth. This means that the
its
diameter as seen from the
Sun would be
just visible as a distinct
globe, rather like a glowing pea in the sky.
THE SOLAR SYSTEM AND BACK
98 Its its
apparent area,
as seen
%7
as bright.
The
Y27
from Amalthea, would be only
apparent area as seen from Earth and
it
of
would therefore be only
brightness would be entirely due to
fall-off in
the smaller apparent area of the Sun and not in the least due to
the lesser brightness of the Sun
Sun
itself,
area for area.
The
pea-sized
Amalthea would be just as bright as a similar-sized section of our own Sun would appear to be if the rest of it were blocked of
off. I
would suggest then that our Amalthea-based viewer would
not find
it
comfortable to stare at the Sun, shrunken though
it
might appear. Amalthea's shrunken brightest object in
To show
its
that, let's
Sun would
be the incomparably
still
sky.
abandon Amalthea's contra-Jovian point for the other hemisphere, where we can see Jup-
a while
and move
iter. If
the Sun were on the other side of the
to
be shining over Amalthea's shoulder,
up the
and
to speak,
so
We
entire visible face of Jupiter.
would
satellite, it
lighting
would be seeing
"full-
Jupiter."
Jupiter
would then be
quarter the
full
a shining glory,
width of the
43 ° across, or nearly one-
would be —20.2
sky. Its brightness
magnitude, or 1100 times as bright as our
full
Moon
seen from
Earth's surface.
The
Sun, however, for
all its
—23.1 and would be 14 times
shrunkenness, has a magnitude of
as bright as Jupiter at its brightest.
What's more, when the Sun and
Jupiter are both visible
Amalthea's surface, Jupiter must be in that
it is
even
less
considerably
dimmer than
less
it is
than
its
from
half-phase, so
and
at the full
is
then
able to compete with the diamond-hard brilliance of the
tiny Sun.
Now
let's
get back to our contra-Jovian point,
where Jupiter
is
never visible and where the Sun can only be compared to the satellites.
The comparison
is
pathetic, in that case.
brightest of the satellites (as seen from
than about half as bright as our
about 32,000 times as bright
full
Amalthea)
Even is
Io,
the
never more
Moon. Amalthea's Sun
as Io at its brightest.
is
THE DANCE OF THE SATELLITES when
Furthermore, all
the Sun
is
in
99
Amalthea's contra-Jovian
sky,
the satellites that are above the horizon are in the half-phase
and are correspondingly dimmer. They are merely washed-
or less
out crescents.
As the Sun swoops east to west,
than Callisto.
from
across Amalthea's contra-Jovian sky
does so faster than any of the
it
The Sun moves
at a rate of
even
satellites, faster
— 30.43 °
per hour (an
exact reflection of Amalthea's motion about Jupiter, as you can see in
Table 21).
The Sun shown
in
therefore overtakes each
Table
25. If
see that the length of time lar satellite is
of the four satellites,
you compare Table 25 and Table it
takes the
Sun
equal to the length of time
it
21,
you
as
will
to overtake a particu-
takes that satellite to
the Sun once.
circle
during the period from solar overtaking to solar overtak-
It is
ing that each satellite goes through
and back
to full
to new.
The
period
its is
remains longest in Amalthea's sky. In the case of
from crescent at satellites
J-I,
which it
J-I,
rising to nearly "half-Io" at setting.
change phase
from new
cycle of phases shortest for
also
can go
The
other
less spectacularly.
Table 25-The Sun and Satellites from Amalthea
Time between Satellite J-I
J-II
Solar Overtakings (hours)
42.45 86.22
J-III
171.7
J-IV
400.5
The Sun is farther from Amalthea than are any of the satellites, when the Sun overtakes a satellite, it can pass behind it
so that
and be
eclipsed.
This would happen every time
if
the Sun's ap-
parent orbit were in the same plane as the orbits of the
However,
all
satellites.
the satellites revolve in Jupiter's equatorial plane
THE SOLAR SYSTEM AND BACK
100
which
to the plane of Jupiter's orbit about the
tipped 3
is itself
Sun. That means that the Sun's path across Amalthea's sky
from the points of intersection there
90
the Sun's path and those of the
in-
such a way that at places
tersects the paths of the satellites in
will
be
gap between
a 3
This
satellites.
big enough to
is
allow the Sun to miss the satellite completely so that there will be
no
eclipse.
However, every once
be only
slightly separated
they are not separated at
How
and an
all)
stance, the
size of the
9'
of arc.
The
between the Sun and Callisto must be
make
pear to
I
2'
am
contact.
of arc
if
The
Callisto
not enough of a
of 6'
satellite
satellite.
of arc,
7.5' if their
to eclipse the
celestial
must
For
in-
and J-IV,
distance, center to center,
edges are to ap-
distance, center to center,
is
calculations precisely, but I
Sun and
Sun and
Sun has an apparent diameter one of
point of intersection
eclipse will then take place.
close to the point of intersection
at the horizon,
will overtake a particu-
(at the actual
be depends on the apparent
than
Sun
in a while, the
the point of intersection that the two will
lar satellite so close to
Sun
must be
less
entirely.
mechanic to make the appropriate
by making some rough estimates (and
hope I'm not too badly
off)
I
have worked out the data
presented in Table 26.
Table 26-Satellite Eclipses of the Sun Satellite
Number of
of Total Eclipses
Time between Total
Sun per Hundred
Eclipses (hours)
Overtakings J-I
8
530
J-II
4
2,100
J-III
3%
J-IV
1
On
5,200
40,000
the average, then, there will be one solar eclipse of
every 400 hours.
The chances
of seeing the
Sun
some sort by one
eclipsed
THE DANCE OF THE SATELLITES satellite or
Such an
another on any given Amalthean day
eclipse
is
101
about
in 66.
1
more common than on Earth and more
is
viewed, too, because the
satellites'
shadows cut across
easily
of small
all
Amalthea, whereas the Moon's shadow narrows down to almost nothing by the time solar eclipse
The
reaches Earth's surface so that any given
it
can be viewed from only a terribly restricted area.
total eclipse doesn't last very long,
motion of the Sun
when J-IV
in Amalthea's sky
utes under the last scrap
Callisto
so rapid. It endures longest
the eclipsing body, since J-IV has the largest ap-
is
parent motion of any of the
the
is
because the apparent
would take
satellites. It
fully 5
min-
most favorable conditions, between the time when
Sun disappeared behind
of the eastern edge of the
and the
scrap of the western edge reappeared
first
other side. For the other
satellites,
the eclipse never
on the
lasts
more
than 2 to 4 minutes.
A
solar eclipse
Earth, in
and
it
not as spectacular on Amalthea as
is
some ways. The Sun's corona
would be hidden by the
satellite.
from Earth
solar eclipse as seen
coincidence that the
is
dimmer than
it it is
is
on
here
(The impressiveness of
rests largely in
a
the extraordinary
Moon and the Sun have almost equal apMoon just fits over the body of the Sun,
parent sizes so that the allowing Still,
points.
show lites
all
the corona to be visible.)
solar eclipses,
as
seen from Amalthea, will have their
As the Sun approaches one of the
as a thin
and shrinking
are in the sky, farther
crescent. If
satellites,
the latter will
one or two other
removed from the Sun, they
satel-
will
be
rather thicker crescents.
As the Sun disappears behind the one satellite, the other one or two would stand out brightly against a sky which now lacked the brightness of the small Sun.
What's more, there would be another phenomenon, ably
more
that— a phenomenon which will take While the Sun is high in Amalthea's contrais nearly full on the other side of Amalthea.
interesting than
a bit of explaining.
Jovian sky, Jupiter
consider-
THE SOLAR SYSTEM AND BACK
102
(When
the Sun
is
at zenith over the contra-Jovian point, Jupiter
is
entirely full.)
This means that the Jupiter-light shining on the the Amalthean sky
is
satellites in
considerable. Ordinarily, a viewer at the
contra-Jovian point on Amalthea would not be aware of Jupiterlight.
During the Amalthean nighttime, the Sun would be on the
other side of the
the
near Jupiter, and Jupiter would be a
satellite,
would be comparatively dim, delivering
crescent. It
satellites in
the contra-Jovian sky.
On
little light
the other hand,
to
when
the Sun was high in the sky and Jupiter was fat and bright on the other side of Amalthea, what light the planet delivered would
be dimmed by comparison with the Sun's
brilliance.
But what about the moment of solar eclipse, when Jupiter is bright indeed and the Sun is suddenly not there to compete. The satellite
behind which the Sun
Amalthea
lit
%
best, only
by
would be
is still
at
its
very
rather impressive.
satellite,
under the circumstances.
that satellite would be black
invisible against the black, airless sky except as a
blot against the Sun. it
side-towardis,
(from the Amalthean view-
particularly impressive
As the Sun passed behind a by contrast and
its
sure, Jupiter-light
4 as bright as sunlight
point) but that It
hidden, has
is
To be
Jupiter-light.
But then, when the Sun disappeared behind would seem to flame out— suddenly
altogether, the satellite
visible in Jupiter-light.
Other
satellites in
as crescents
the sky at the time would
still
by sunlight but the remainder of
facing surface would be
lit
by
be marked out
their
Jupiter-light and, with the
momentarily absent from the
sky,
Amalthea-
Sun
itself
that Jupiter-light would be
more clearly visible. Under favorable conditions, our own crescent Moon has the rest of its body very dimly lit by earthlight ("the old Moon in the new Moon's arms") but it must be remembered that Jupiter-light is
considerably brighter than earthlight under comparable condi-
tions.
And
would be
in addition, the sunlit portions of the Jovian satellites
less brilliant
than the sunlit portions of our Moon.
THE DANCE OF THE SATELLITES So
and
far I
have described two types of
IO3
eclipses, satellite-satellite
satellite-Sun. Let's consider a third type.
Imagine the Sun to be
circling
about Amalthea
observer on Amalthea's surface) and
on the hemisphere facing
let's
by an
(as seen
imagine ourselves to be
Jupiter.
Each time the Sun makes its circle, it must pass behind Jupiter's swollen globe and would spend 1.4 hours behind it, too, so that there would be an eclipse for nearly one-quarter of the daylight
Nor would
period, during every daylight period.
there be any
Jupiter-light bathing Amalthea's surface, for during the period of
the eclipse, Jupiter would be in
its
"new" phase, presenting only
dark side to Amalthea.
its
On
Jupiter's contra-Jovian side,
such an eclipse would never be
directly seen, because Jupiter itself
the
Sun
is
is
never directly seen.
in the contra-Jovian sky there
is
no chance
When for
an
momentary ones by the satellites). The contra- Jovian side of Amalthea gets the full 5.92 hours' worth of sunlight— one-third more than the Jupiter-side gets. However, the eclipse of the Sun by Jupiter can be detected indirectly, for Jupiter's shadow falls on any of the satellites that may be on the night side of the planet. eclipse (except the occasional
From Amalthea's
contra-Jovian side,
it
will
be
possible, at in-
tervals, to see one satellite or another move into the Jovian shadow and blink out. Nor will it be lit by Jupiter-light, for, of course, it will be facing Jupiter's night side and the huge planet
will I
his
be in the "new-Jupiter" phase. suppose an observer on Amalthea's contra-Jovian
knowledge of the Sun and the
and from
would be able its size
side,
from
which he could
see,
manner in which each satellite on occasion when the Sun was not in the sky,
his observations of the
would be eclipsed of
satellites,
just
to
deduce the existence of Jupiter and get an idea
from those
eclipses,
even
Amalthea's other side to see for himself.
if
he never traveled to
THE PLANETARY ECCENTRIC
8
Some months
my wife and
ago,
very funny one-act plays.
We
I
saw Plaza Suite,
a trilogy of three
enjoyed them hugely in themselves,
and we enjoyed them the more because the two leads were such favorites of ours and so good. There are very few people who are not just a little star-struck,
my wife has a feeling hidden deep within her that me as a tool with which to meet those few certain
of course, and
she can use
stars that strike her.
science-fiction fan, self
.
.
if
that
I
all,
I
she reasons,
if
one of them
is
a
walk boldly up and introduce my-
.
The one what
After
and
catch
is
refuse to lend myself to this. After
all,
they are not science-fiction fans? Think of the humilia-
if
tion!
So
I left
the theater, holding her elbow firmly and ignoring her
plaintive plea that
magic name.
We
I
make my way backstage and announce my
went
to the restaurant next door instead for a
cup of coffee while she glared daggers at me.
And
waitress told us in great excitement that the entire
then the
company
of
Plaza Suite was in that same restaurant.
Can I said,
I
fight Fate?
I
sighed and removed
resignedly, "Til
chance
it."
my
napkin. "All right,"
THE PLANETARY ECCENTRIC I
IO5
my
walked over with a charming smile, handed over
program
booklet for autographs and casually introduced myself, pronouncing each syllable of
bombed
say, I
my name
with the greatest care. Needless to
completely. There was no sign that any one of the
crowd at the table had heard of me but as I drew back in chagrin, someone suddenly rose and dashed forward, shouting, "Gertie!"
My
wife looked startled, then cried out, "Nate!" and, behold,
they were grabbing at each other excitedly. Nate was her
whom
many
first
and he was right there at the table. She didn't need me at all. She had a great time and I stood to one side, shifting from foot to foot, and experienc-
cousin
ing,
she hadn't seen in
but not enjoying,
my
years
unaccustomed
role as husband-of-the-
celebrity.
But we should all learn from our misfortunes and humiliations and to me it was just another case of getting practice in shifting
The
viewpoints.
how many And it
universe does not revolve about me.
(I
forget
separate times I've very temporarily learned that.)
doesn't
about
revolve
though you'd never guess
it
us,
either,
collectively,
even
from a casual glance at our astronomy
texts.
For instance, any go around the little
As
under 12
No, they
long
years.
it
takes Jupiter to
And do
they say: a
don't.
happens, Jupiter goes around the Sun in one year by def-
it
inition:
very
under 12
little
Eooo mcn ^ You P^fer).
say that the
were M.oo>ooo centimeters tall (or > This means that if they were of average height to begin with, all
their
measurements have shrunk down to
they were.
To
% 7>ooo>o 00
of
what
themselves, with their shrunken atoms and their
diminished mass, they seem perfectly normal. They and their
submarine seem, to themselves, to be of normal
size
while the
THE INCREDIBLE SHRINKING PEOPLE entire universe outside the
ments by 17,000,000
submarine has increased
141
measure-
its
in every direction.
Consequently, the blood vessels are huge conduits, the white corpuscles are big enough to swallow a submarine whole without
discomfort, and so on.
The
picture
went that
anyway, but
far,
what about atoms themselves?
An atom
about M.oo>ooo700o centimeter
is
in
diameter.
In-
measurements 17,000,000 times in all directions and it becomes about % of a centimeter across. Since the important crease
its
gases in the atmosphere (oxygen
and nitrogen) are made up of
molecules which each contain two atoms, the molecules in ordinary,
unshrunken
air
would seem
ellipsoids that are
meter across at their longest diameter— at
%
of a centi-
shrunken
least to the
people.
This means that the unshrunken atoms and molecules would
be big enough to see cerned.
The
At one
as far as those
point, the submarine runs short of air
a snorkel into the patient's lungs air.
But the snorkel opening
the
air
long
it
shrunken people were con-
movie, however, does not take that into account.
is
and
not
fills
much
molecules in the patient's lungs.
would take
to
draw
air
up
its
and so
sticks
it
tanks with fresh
larger in diameter
than
Can you imagine how
through the snorkel under those
A slow leak in a tire would be speedy in comparison. What's more, once the ship is filled with unshrunken air, how do you get those huge molecules up your nostrils and into your conditions?
own shrunken
And what do you do with those your lungs? Can your own shrunken red
lungs?
once they are in
molecules corpuscles
handle them? I
had
didn't think of that
till
after I
had
finished the novel
to go back in a wild perspiration to revise several pages.
to use a device to shrink
before pulling
it
some
and I I had
of the air in the patient's lungs
through the snorkel and into the ship.
Here's another point. The men on the shrunken submarine communicated with the outside world by radio. However, the radio was shrunken and the radio waves it emitted would have
THE SOLAR SYSTEM AND BACK
142
only
% 7>ooo>o 00
shrunken
state.
might seem
the wave length they would have had in the un-
The
radio
like radio
would be emitting
They
light waves.
waves to the operator on board the sub-
men
in the
communication
radio-
marine, but they would be tiny flashes of light to the
unshrunken world and using them
for
fashion would be tricky.
And how would
our
men on
the submarine see?
By
the light
waves produced by their shrunken light sources? But these light
waves would be
gamma
rays to the outside
whose blood stream they were
in
enough
to
damage him,
I
hope, but
world— to the
cruising, I
patient
instance.
for
didn't bother to
Not
do any
calculations. I let
the radiation bit go because (once again)
I
thought of
too late and was lazy enough to feel that no one would catch
it.
it
I
underestimated my readers, of course. One sharp-minded young man picked it up and was down on me at once. I had to write back a confession of guilt.*
The movie-makers had
the heroine (Raquel
by antibodies, but hadn't the
faintest notion of
Welch) attacked what an antibody
like if it were properly enlarged. Of course, with Miss Welch on screen, who studies the antibodies, anyway? The antibodies are, of course, protein molecules and I imagined
would look
they would look like glimmering
little balls
of
wool perhaps two
inches across on the scale of the shrunken people. feel like balls of
peptide chains in place should be quite flexible and
Then,
I
had them
wool, too, for the hydrogen bonds that held the
too, the
resilient.
movie makers forgot to consider that the thin
cell membranes would not be thin at all to the shrunken people. At one point, one of the men must work his way out of the capillary and into the lung. In the movie, there's no particular problem in doing so. You just slice through the paper-thin membranes *
Since this article appeared, I received several letters pointing out additional involving electric forces, in which radical shrinking introduces
subtile ways,
insoluble dilemmas.
THE INCREDIBLE SHRINKING PEOPLE separating the two. After
membranes
all,
143
%o>ooo of an
are only
inch thick.
membrane would be scale. The plot made it
Sure, but to the shrunken people, the
something
like
40 yards thick on their
necessary for the hero to cross that thickness and
much.
yards was a bit
the book and
let it
I
go at
cheated and called
it
I
thought 40
"several yards" in
that.
What's more, there was the matter of surface tension. In the body of a quantity of liquid, each molecule is weakly attracted by all
move
cules
At the
the other molecules.
all
directions
The
attractions
come from
and cancel each other out so that individual mole-
freely as
though they are not being attracted at
surface of the liquid, a molecule
The
molecules within the liquid.
is
attracted only
all.
by other
sparse scattering of air molecules
outside the liquid has hardly any effect.
Molecules on the surface endure a net inward
and face.
it
takes an expenditure of energy for
For that reason, there
That
small as possible. freely,
is
why
What's more, far as
A
as
is
"tear-
air resistance.)
since all the surface molecules
push inward
as
closer to-
a
crowded subway car at
try to separate these
crowded-together mole-
gether, like people trying to
To
sur-
be
sphere has the smallest pos-
volume. (A falling raindrop
they can, they force themselves (so to speak)
the rush hour.
on the
small quantities of liquid, floating
assume a spherical shape.
shaped" because of
pull, therefore,
to stay
a tendency for the surface to
is
sible area of surface for its
them
push into
more energy than trying to separate ordinary molethe body of the liquid. This extra clinging-together of
cules takes
cules in
surface molecules
is
spoken of as "surface tension" and
though the liquid had a very
it
is
as
fragile skin covering its surface.
Tiny objects are not heavy enough to break that skin and small insects
can go skittering over a water surface, not because they are
floating (if they rise to
were within the body of water, they would not
the top) but because they are supported by the surface-
tension skin.
THE SOLAR SYSTEM AND BACK
144
Well, now, face tension, I
insects are light
if
what about
didn't dare calculate
would be
so great that
sur-
objects the size of our shrunken people?
surface tension of unshrunken
what the
might seem to be
liquids
enough to be supported by
shrunken people.
to the
my
I
suspect
it
heroes simply couldn't break through
the surface of the liquid blood into the air within the lung.
The albeit
necessities of the I
made him have
To
far
to let
him through,
no one has written
would be an insuperable
explain one last point,
when
So
difficulties.
say that the surface tension
tury,
me
movie plot forced
let's
in to
barrier.
go back to the nineteenth cen-
there were indeed great scientists who, like Hollywood
movie-makers, disbelieved in the existence of atoms. In the case of the scientists, ever,
it
was not a matter of
blissful ignorance,
how-
but of cogent thought.
The atomic in 1803
theory had
first
been advanced
by the English chemist John Dalton
in
its
modern form
as a convenient
way
of
explaining various chemical phenomena. Throughout the nine-
teenth century, the concept of atoms had been more and more successful in explaining
what went on
inside the test tube.
end of the century, chemists were even making use of formulas" for the more complicated molecules.
By
the
"structural
Not only
did they
count the number of atoms of the various different kinds within a particular molecule; they even placed those
arrangements in three dimensions, Naturally,
atoms
it
was almost inevitable
really existed. If
matter behave as though if it
Nevertheless,
it
much
atoms
in specific
Tinkertoy structure.
for chemists to believe that
atoms did not
tended existence explain so
thoroughly,
like a
exist
how
could their pre-
so conveniently?
How
could
were atomic in so many ways and so
were, in fact, not atomic?
some
scientists
maintained
it
was not wise to
stir
beyond the measurable phenomena. All the nineteenth-century knowledge of atoms was
indirect.
Atoms were
too small to be
seen or sensed in any direct way, and while they might be very
THE INCREDIBLE SHRINKING PEOPLE model
useful as a
lead scientists
The
to focus thought, they
who
chemist Wilhelm Ostwald. still
changed
his
Brown was
The
felt)
mis-
last to refuse
was the German physical
twentieth century opened with
vigorously maintaining the anti-atomic view. Yet he
mind, at
began
It
was
(it
literal existence.
argue in this way, the
last great scientist to
to accept the literal existence of atoms,
Ostwald
might
too easily believed in their
145
last,
and
here's
how: Robert Brown.
1827 with a Scottish botanist,
in
and
at
one time he was studying
a suspension of pollen grains in water
under a low-power micro-
He
scope.
They
found he had trouble focusing, for the grains
did not
jiggled
move
randomly
Brown and
interested in pollen
felt
all
jiggled.
purposefully in a particular direction; they over the
lot.
realized that the pollen grains
were
alive, if
dormant,
that the motion might be a kind of manifestation of
However, he watched dye similar size
particles
when suspended
ratically, too.
in water
and they
jiggled
about
Anything that was small enough would
suspension, and the smaller
it
life.
(indubitably nonliving)
was, the
of er-
jiggle in
more marked was the
jiggling-
All that could be
enon
a
by Brown, and
Why In
done
at this time
was to give the phenom-
name, since there was no explanation.
not the
it
call it
also involved the erratic
It
was discovered
motion of
particles.
"Brownian motion" then? the Scottish
1860s,
physicist
James Clerk Maxwell
produced an impressive explanation of the properties of gases terms of randomly moving particles, and for the
first
in
time the
atomic theory explained physical phenomena as well as chemical
phenomena. At once the thought arose that randomly moving particles in a liquid might be shoving the larger particles in suspension this way and that. In short, the grains of pollen or dye were being bombarded by
water molecules and
it
might be that which was producing the
Brownian motion.
Look
at
it
this
way.
We ourselves are being bombarded
from
all
THE SOLAR SYSTEM AND BACK
146 sides
by
air
molecules
or, if
we
by water molecules.
are in water,
However, at any given moment, we are being struck by enormous
numbers from itself out.
the different directions and the effect cancels
all
We are struck by no more from one direction
the opposite direction.
It
may be
more
that a few
than from
strike
from the
from the west, but the individual molecules are so tiny
east than
mere few out of the astronomical numbers immeasurably small. Of course, if a lot more strike
that the effect of a available
is
from the
east than
chance that a
lot
of the molecules
from the west, we
more is
also
will
do so
(or shrinking
their point of view the universe
molecules of
and water
air
and fewer
strike
them
bombarding mole-
will
and
larger, too.
our people reach the microscopic, they are being bom-
many
from east than from west
tiny bodies will feel
them
The
in a given small instant of time.
barded by BB-shot and not by strike
and the
Because they themselves get
as well.
individual molecules get larger
When
anything).
getting larger,
is
smaller, they present a smaller target to the
cules
random motion
immeasurably small.
But consider our shrinking people
From
but the
will feel the push,
in the sheerly
west,
and
it.
A
in the next
it
Now
a few
more
be important and
their
of them. will
if
preponderance from the east shoves
moment
a preponderance
from above
push them downward, and so on.
The random bombardment by tion in the
first
molecules would explain the mo-
place, the erratic nature of the
second, and the fact that the effect was
motion
in the
more pronounced the
smaller the floating object in the third.
Men
like
just talk.
Ostwald were not impressed by
To make
it
more than
talk
this
argument.
chances of imbalance in molecular bombardment and the the
effects.
It
was
one ought to calculate the
In short, there would have to be a
strict
size of
and rigorous
mathematical analysis of Brownian motion that would explain quantitatively in terms of the
Then
in
random bombardment
1905, such an analysis was produced,
other than Albert Einstein.
it
of molecules.
and by none
THE INCREDIBLE SHRINKING PEOPLE
147
According to his equation, particles suspended in a tainer of liquid ought to
behave
tall
in response to a balance
con-
between
the force of gravity and the effect of Brownian motion.
Gravity pulled downward and molecular motion kicked in directions,
including upward.
volved, the particles
motion were
all
would
If
gravity
all settle
were
all
all
that were in-
to the bottom. If
Brownian
that were involved they would spread out evenly.
In a combination of the two, they would spread out, but pile up
more and more densely toward the bottom. The more massive the molecules, the greater the Brownian motion particular size at a particular temperature
for
objects of
a
and the smaller the
extent to which they would crowd toward the bottom. Einstein was merely a theoretician, however.
He
was
satisfied
and he left it to others to check it against observable phenomena. The one who followed it up was a French physicist, Jean Baptiste Perrin. In 1908, he suspended small particles of gum resin in water and counted the number of particles at different levels. He found that the numbers increased to produce the equation
as
he worked downward exactly
in
accordance with Einstein's
equation, provided the molecules of water were given a certain
mass.
Not only had he
verified Einstein's explanation of
motion, but he was the
first
to
Brownian
work out a reasonably accurate
measure of the actual weight of individual molecules.
Ostwald was now faced with an observable individual molecules.
By
effect
produced by
looking at suspended objects in water
effect, see them being struck by inThat supplied his rigid requirement for direct observable evidence and he could no longer deny the existence of
jiggling around,
he could, in
dividual molecules.
atoms. Perrin received the 1926
Nobel Prize
in Physics for his work.
(Einstein had gotten his, for other work, in 1921.)
This brings
me
back to Fantastic Voyage. In the movie, the
shrunken submarine moves through the blood stream precisely as
THE SOLAR SYSTEM AND BACK
148 it
would
if it
were of normal
That would be
rent.
so
moving through an ocean
size
no atoms
there were
if
or
if
cur-
atoms were
infinitesimally small.
But there
The
are
atoms of
size
comparable to the shrunken
ship.
ship ought therefore to be jiggling from side to side, back
and
up and down, and every direction in between, through the effect of Brownian motion. This would happen in even more pronounced fashion to the individual people on those occasions when they left the ship to swim around in the blood stream. I couldn't actually allow much Brownian motion in the novel. forth,
would have introduced too many complications (bad seasickness for one thing). I did mention it, though, and allowed some It
show
jiggling at the start, just to
then
I
ignored
All this
of
my
fiction
to
do
may
I
and who now think Don't think that
not necessarily require Despite
there;
and
it
felt
the impulse to write science
advanced degrees in science
requires
for a
moment. Good
science fiction does
the errors, inconsistencies, and oversights in the
all
penseful, fast-moving, I
ought to be
all this folderol.
movie Fantastic Voyage, a bit while
it
cause alarm and despondency in the hearts of some
Gentle Readers who have
so.
knew
it.
thought
I
and
it
delightful.
was a
The
lot of fun, very sus-
errors didn't
bother
me
was watching.
What's more,
if
someone
else
had written a novel based on the errors, it would
movie and had not bothered to correct any of the still
easily
have made an exciting
It's just that,
were there and
I
in
had
ing science fiction to say that
only way.
I
my own
story.
case, I
to correct them.
and
consider
it's
know the errors my personal way of writ-
happened It's
to
not the only way. Candor compels
my way
the best way, but
it's still
me
not the
B
— CHEMISTRY
THE FIRST METAL
11
I
am
sometimes asked how
essay.
The answer
is
Sometimes, though,
I
I
decide on the subject for a science
and straightforward:
clear
do happen
I
don't know.
to catch a fugitive glimpse of
the mental processes involved before they whiff away and depart forever.
Thus, several weeks ago,
I
came
across
some comments
chemistry journal concerning the metal, gallium. This interesting metal
on two counts.
It
is
in a
a very
played a melodramatic role in
the working out of the periodic table, and
it
has a very interesting
melting point.
That gave
rise to
the possibility of an essay on the periodic
ble or, alternatively, to
few moments,
I
ta-
one on melting points of metals. For a
speculated idly on what could be done with melt-
ing points. It seemed to
me
melting point of gallium,
I
that
would
I
if
first
were going to discuss the
have to discuss the melting
point of mercury.
And to
if I
discussed the melting point of mercury,
mention a few other things about
it,
I
would have
notably the fact that
it
was one of the seven metals known to the ancients. In that case,
how about an
essay,
first,
on the ancient metals?
THE SOLAR SYSTEM AND BACK
152
That
what
is
my way And
up
am now
I
to mercury,
that
is
how
I
sitting
down
and then
to write, intending to
work
to gallium.
decide on subjects to write
about— at
least,
in this case.
The order)
seven metals
known
to the ancients were (in alphabetical
copper, gold, iron, lead, mercury,
:
covery of each of these strongly suspect
that was the
Why
it
first
is
lost
silver,
and
tin.
The
in the mists of the past,
was gold that was discovered
first.
It
dis-
but
I
was gold
metal.
Gold can occasionally be found as a glittering little nugget. Its bright and beautiful yellow color would easily attract the eye and it would become an ornament at once. Once handled, gold would almost at once show itself to be a remarkable substance, much different from the rock, wood, and bone that mankind had been working with for hundreds of thousands of years. Not only would it have a shiny color, but it would be considerably heavier than an ordinary pebble of the same size. Then, too, suppose the finder wished to work the nugget into a more symmetrical shape. To shape a stone, he would make use of not?
careful strokes with a stone chisel. Flakes of thin stone split off
The merely
would
the object being shaped.
gold would not behave in this manner.
make
The
chisel
would
a dent in the gold. If the gold were beaten with a
mallet, the metal
would not powder
as a
pebble would;
flatten into a very thin sheet. It could also
it
would
be drawn out into a
very fine wire, which stone certainly could not do.
Other metals were eventually discovered— other objects which had luster and unusual weight and which were malleable and ductile. None was as good as gold, though. None was as beautiful,
or as heavy.
shine
more
What's more, other metals tended
or less quickly
if
exposed to
air
to lose their
over periods of time;
gold never did.
And rare.
gold had another property which added to
This was
true, to a
somewhat
lesser extent,
its
value;
it
was
however, of the
THE FIRST METAL other metals, too.
The
Earth's crust
153
primarily rock, and the oc-
is
The
metal nugget was occasional indeed.
casional
"metal" seems to
come from
very
word
the Greek word metallan, meaning
"to search for/' a tribute both to
and
its rarity
desirability.
Modern chemists have worked out the composition
the
of
Earth's crust in terms of each of the various elements, including
the seven ancient metals. Here in Table 32 are the figures for the
grams of metal per tons of Earth's
seven, given in
crust,
and
in
order of decreasing concentration.
Table Metal
32
Concentration (g/ton)
Iron
50,000
Copper Lead Tin Mercury
As you
see,
centration
80 15 3
0.5
Silver
0.1
Gold
0.005
gold
is
by
far the rarest of the seven metals.
g ram P^r ton
of 0.005
is
equivalent to
1
A
con-
part
in
200,000,000. Still,
the total quantity of gold
entire crust.
At
is
sizable
this percentage, the total
if
one considers the
mass of gold there
is
about 155,000,000,000 tons.
There
is
gold in the ocean, too, in the form of submicroscopic
metallic fragments,
gram per
ton,
which comes to a concentration of 0.000005
making a
mass in the oceans of nearly
total gold
9,000,000 tons.
The
gold in the ocean
is
so
dilute
that
it
extracted at anything but a large loss. Therefore
been extracted from the ocean. of gold, but the soil
is
The
soil
cannot yet be
no gold has ever
has a larger concentration
harder to work with.
If
gold were evenly
THE SOLAR SYSTEM AND BACK
154
spread throughout the crust, that gold, too, would be unavailable to us.
But the gold profitably,
is
not evenly spread. There are occasional acces-
where the gold content
sible regions
high enough to be mined
is
even with primitive equipment, and where reasonably
pure metallic gold can sometimes be found in sizable nuggets.
But only
a tiny fraction of
the gold
all
is
thus
made
available.
Nothing has been
so avidly searched for as gold through all six
thousand years of
civilized history; yet
estimated that the total
amount
with
of gold
ground by mankind amounts to only 50,000
all
that search
extracted tons.
it
is
from the
What/ s more,
the world's mines are producing gold at the rate of only about a
thousand tons a year (half of
in
it
South Africa). Even
so,
the end
of Earth's reserves of minable gold seems to be in sight. It
would be
interesting to see
served to affect
human
how
small a quantity of gold has
history in so
enormous
a way. If all the
gold so far extracted from the Earth were packed into a cube, that
cube would be 290 feet on each plate an area the size of
only be about
1
side. If all that
Manhattan
It
would
millimeter thick. (That puts another view on the
old immigrant notion that the streets of
with gold.
gold were used to
Island, the layer of gold
would have
to be, at best,
New
York
are paved
an awfully thin pave-
ment.)
The first
question then arises as to
metal to be discovered
The answer
lies in
if it
why
gold should have been the
was the
rarest of the seven.
the comparative activity of the metals, their
comparative tendency to combine with other elements to form nonmetallic compounds.
The
activity of metals
can be measured as "oxidation potential"
in volts (because electric currents can
make
metallic atoms plate
out as free metals or go into solution as ions).
drogen
The element
hy-
(which has some metallic properties from a chemical
standpoint)
is
arbitrarily given
an oxidation potential of 0.0
volts.
THE FIRST METAL
155
Elements which are more active than hydrogren have a positive oxidation potential; those
less active, a
negative one.
Here, then, in Table 33, are the oxidation potentials for the seven ancient metals:
Table Metal
Oxidation Potential (volts)
Iron
Silver
+0.44 +0.14 +0.13 -0.34 -0.79 -0.80
Gold
-1.50
Tin Lead Copper Mercury
As you and
is
see,
gold
is
by
therefore
form. Thus, gold
is
by
So
likely to it
all.
most
likely to exist in
free metallic
common than iron, atom by atom, but more common than iron nuggets. Indeed,
far less
but for one factor which not be found at
far the least active of the seven metals,
far the
gold nuggets are far
more
33
I will
come
be noticed than the
happens that while
silver
would
to soon, iron nuggets
Furthermore, the yellow gleam of gold
is
much
dirty gray of iron.
and copper objects
(also
among
more inactive metals) can be found in predynastic Egyptian tombs dating as far back as 4000 B.C., gold objects, it is thought,
the
antedate that mark by several centuries. In early Egyptian history, silver was more expensive than gold,
simply because
it
was
rarer in
nugget form.
we might generalize that the ancient metals are the metals. Yet we are bound to ask, then, if there were any metals not known to the ancients. The answer is: Yes.
Indeed, inert inert
There are
six
metals of the "platinum group"—platinum
itself,
then palladium, rhodium, ruthenium, osmium, and iridium— that should qualify. Platinum, osmium, and iridium are somewhat more
THE SOLAR SYSTEM AND BACK
156
inert than gold, even,
Why,
silver.
and the others are
known
then, were they not
tempting to blame
It is
them— ruthenium,
it
on the
at least as inactive as
to the ancients?
Four of
rarity of the metals.
rhodium, osmium, and iridium— are consider-
ably rarer even than gold, with concentrations in the crust of only 0.001
gram per
ton. They, along with rhenium, have the distinc-
tion of being the least
discovered— but that
Yet platinum
mon.
common
metals on Earth.
unique distinction of being the
also the
as
is
last stable
element to be
another story.)
is
common
as gold,
and palladium twice
gold nuggets can be found, then,
If
(Rhenium has
why not
as
com-
nuggets of
platinum? Or palladium?
For one thing, yellow gold
far
is
more noticeable than white
platinum. For another, the best platinum ores are located no-
where near the ancient sites of civilization in the Middle East. Then, too, I rather suspect that platinum nuggets were indeed found now and then— and mistaken for silver. Platinum is far less malleable than tive
silver
and
is
not easily worked.
can see the primi-
metalworker looking at such nuggets in disgust and mutter-
ing "Spoiled silver" as he tosses
The apparent resemblance It
I
was
first
them away.
to silver
marks platinum to
clearly recognized as a distinct
a Spanish chemist,
Don Antonio
this day.
metal in 1748, when
de Ulloa, described samples of
the metal which he had located in the course of his travels
through South America. Spanish word for
name)
Nor
silver.
He named
it
"platina" from plata, the
So platinum remains forever
is it
common
surprising, in
view of
all this,
that iron, by far the most
of the seven metals— five hundred times as
the remaining six put together— lagged in
all
the
(at least in
a kind of silver.
rest.
After
all,
it
common
as
some ways behind
was the most active of the ancient metals,
the most apt to be in combination, the most difficult to loose from that combination.
That
it
was known at
all
may have been
catastrophe millions of miles from Earth.
the result of a cosmic
THE FIRST METAL After
all,
as
as
far
157
chemical principles are concerned, iron
should occur on Earth only in the form of nonmetallic com-
pounds, never as the free metal. Yet that's not the way
There
is
ward the
much
so
iron
itself, this
it is
and
seems that one of them
it
may have exploded
(the one, presumably, between
Jupiter, the orbit of
which
plosion
a
must be other
doesn't affect Earth's crust, but there
planets with such a nickel-iron core
fragments of that explosion).
is
metal, nickel, in a 10-to-i ratio.
its sister
is
it is.
so concentrated to-
mass of the planet
center, that one-third of the
liquid core of iron plus
In
on Earth, and
Mars and
now marked by the asteroids, The smaller fragments of that
bombard the Earth, and some
the ex-
of
them
are the fragments
is
large
enough
of the nickel-iron core. If the fragment
it
survives
the friction of the atmosphere and strikes the crust, where
it
lodges as heaven-born "nuggets" of iron.
Small pieces of nickel-iron (undoubtedly meteoric in origin) are
found
in
Egyptian tombs dating back to 3500
b.c.
They
are there
in the guise of jewelry.
As long they were
be used when found as nuggets,
as metals could only
bound
to be excessively rare, but
some time before 3500
the true discovery of metals was made.
b.c.
could stumble across a nugget. nize
The
fool, after all,
took a man, however, to recog-
It
what had happened when copper nuggets were found
ashes of a It
Any
fire
that
had been
built
in the
on a blue stone.
was a daring thought that from rock one might gain metal. science of metallurgy began
and men began to look not
for
metal only, but for metal ores— for rocks that, on heating in a
wood It
fire,
would
yield metal.
was copper that was
chiefly
became the wonder metal of the
mon it
as
as gold,
produced age. It
in this
manner, and
was 16,000 times
once the ores were taken into account.
as
it
com-
And though
compounds in the ore, it was not so active bound in those compounds. A gentle nudge,
did occur as rocklike to
be
tightly
chemically speaking, would suffice to pry the copper loose.
Copper alone was
ornaments and for some But then another accidental
suitable merely for
utensils— too soft for anything
else.
THE SOLAR SYSTEM AND BACK
158 discovery
must have been made. Tin and
as copper ores were,
some
if
ores could be handled
ores contained both copper
the mixed metal ("alloy") that resulted was
tin,
tougher than copper alone. cients learned to
mix
We
and
ores of copper
tin
the Bronze Age. In the Middle East, the
for
the Bronze
Tin was the bottleneck here. and the still
tin reserves of
navigators, the best
way out
their
The
an-
Thus was
site of
b.c.
initiated
man's oldest
and endured
It is
% 5 as common as copper,
only
the Middle East ran out while copper was
As
had
to
be scoured
a result, the far-distant
The
for tin.
Phoenician
and most daring of the ancient world, made
to the
"Tin
Isles" for
the purpose.
Phoenicians kept the secret of the location of the Tin
throughout their history, but sailing
The
years.
available in comfortable amounts.
corners of the world
and
harder and
on purpose and to
Age began about 3500
something over two thousand
much
the alloy "bronze."
call
use the bronze they obtained for war weapons.
civilizations,
much
it
Isles
seems quite certain that they were
out into the Atlantic Ocean and northward to Cornwall,
on the southwestern extremity of the Cornwall
is
island of Great Britain.
one of the few regions of the Earth which
is
rich in
mining, some 3,000,000
tin ore. In twenty-five centuries of steady
tons of tin have been removed from the Cornish mines and the area
is
not yet exhausted. Nevertheless,
minute compared to those of the
its
output these days
relatively
is
untapped mines of
Malaysia, Indonesia, and Bolivia.
Yet even while bronze was carrying
knew
tools. It
now and
it,
the ancients
much
better for
war weapons
was iron— those metallic lumps that were picked up
then, a very rare
now and
There were, of course, iron
and
before
very well that there was a metal that was harder and
tougher than bronze and potentially
and
all
tin ores. Indeed,
common. The
it
then.
ores, just as there
were copper ores
was obvious that iron ores were extremely
trouble was that iron
(much more
active than cop-
THE FIRST METAL per) held on to
its
compound
place in the
The
techniques for iron.
as was coaxed out of the ore was riddled with gas bub-
was
bles. It
firmly.
would not do
that sufficed to extract metallic copper
Such iron
159
Special
and good
brittle
techniques
for nothing.
involving
hot
particularly
needed, along with high-quality charcoal. Even
were
flames
when temperatures
were reached that sufficed to melt the iron and drive out the bubbles and, indeed, prepare
it
in pure form, the end-product
was
disappointing. Iron obtained from ore was not nearly as hard as
the meteoric nuggets, and
it
did not hold nearly as fine an edge.
The difference was that meteoric unknown to the ancients).
iron contained nickel (a metal
But then processes were developed that produced iron into which some carbon from the charcoal was introduced. In kind of
steel
was produced and
that, at last,
effect, a
was the metal that
was needed. It
was sometime about 1500
good iron
in useful quantities
when
b.c.
the secret of producing
was developed somewhere
in the
southern foothills of the Caucasian mountains. This was in what
was known
as the
kingdom
Ark landed). The area was, Hittites, tite
of Urartu (the "Ararat" at the time,
whose power center was
kingdom
where Noah's
under the control of the
in eastern Asia
Minor. The Hit-
keep knowledge of the new technique a
tried to
monopoly, but the exploitation of
this
new weapon was
slow. Be-
fore the Hittites could really turn the metal into a world-beating
military resource, they
of civil
The
were themselves beaten by a combination
war and invasion from without. fall
of the Hittites
of iron technology
fell
came soon
after 1200 b.c.
and the
secret
to Assyria, the land just south of Urartu.
Gradually, the Assyrians developed iron to an unprecedented extent
and by 800
into the field.
nium and syrians
b.c.
they were putting a completely iron-ized army
They
for a similar purpose.
swept
all
we
stockpile ura-
For two hundred
years, the As-
stockpiled iron ingots as
before
them and
built the greatest empire the
:
THE SOLAR SYSTEM AND BACK
l6o
Middle East had yet seen— until
their victims learned iron tech-
nology for themselves. It is interesting to note,
monness,
is
not the most
by the way, that
common
iron, despite its
metal on Earth. There
com-
is
one
metal more common, but also more active. In consequence,
it
lagged even farther behind in development.
The most common metal centration of which
mon
as
iron,
but
is
in Earth's crust
is
81,300 grams per ton.
its
oxidation
aluminum, the con-
It is 1.6
potential
is
times as com-
+1.66,
which
is
considerably higher than even that of iron.
This means that the tendency of aluminum to form compounds
and that it is much more difficult compounds than it is to force iron of those out of its compounds. Moreover, no aluminum nuggets fell from the sky to hint to mankind that such an element exists. As a result, aluminum remained completely unknown (as a is still
greater than that of iron,
to force
aluminum out
free metal) to the ancients. It wasn't until 1825 that the first piece
of
aluminum metal
(quite impure) was forced out of a
by the Danish chemist Hans Christian Oersted.
And
it
compound wasn't
till
1886 that a good method was discovered for producing the pure metal cheaply and in quantity.
Metals, generally, are denser than stone. in ounces per cubic inch,
we
find (see
Table
If
we measure
Table 34)
34
Density
Metal
(ounces/ cubic inch)
Tin
4.2
Iron
4.6
Copper
5-2
Silver
6.1
Lead Mercury Gold
6.6 7-9 11.3
density
THE FIRST METAL
l6l
Since the typical rock has a density of about 1.6 ounces per cubic inch, even the least dense of the seven metals
dense as rock, while gold
High density has
is
its uses. If
you wish to pack a
denser the metal the better. Gold
is
cury, being liquid,
That
would be too hard
came the
it is
it is
too valuable. Mer-
to handle.
leaves lead as a third choice. It
and
metal,
weight into
the best in this respect but no
going to use gold as routine ballast;
is
lot of
you would use metal rather than stone; the
a small volume,
one
2.5 times as
is
about seven times as dense.
is
relatively cheap, for a
four times as dense as rock. Lead, therefore, be-
The
representative of heaviness.
phrase "heavy as lead"
has entered the language as a cliche, which has
much more
force,
through sheer repetition, than the phrases "heavy as gold" or
(We mean
"heavy as platinum."
"dense" rather than "heavy," but
never mind.)
we
Again, can't
and
speak of "leaden eyelids" to imply sleepiness that
be fought
difficult
To
off;
"leaden steps" to indicate a walk
made
slow
by the weight of weariness or sorrow.
hang
force a line to
vertically,
one would want to put a
weight at one end, so that the force of gravity would stretch the line straight
up and down.
A lump of lead would be a
compact way
of supplying the weight.
The what
Latin word for "lead"
a
"plumb
line"
lead to a line you as far as possible,
must
wanted
is
plumbum and now you
be. Since to
can see
you would attach a piece of
throw into the ocean and have sink
you see what "to plumb the depths" means.
Again, since the ancients believed that the heavier an object the faster faster terials.
it fell, it
seemed
to
them
that a lead weight
than the same-sized weight made of other
less
would
fall
dense ma-
So you see what "to plummet downward" means.
Finally, since a lead
weight makes a line completely
there grew to be a tie-in between lead
now you
see why, in a
and completeness,
Western movie, the old rancher
vertical,
so that
says to the
young schoolmarm, "By dogies, Ah'm shore plumb tuckered out,
THE SOLAR SYSTEM AND BACK
l6l
missie." (At least
you know why he says
it if
you know what the
other words mean.) All this remains, even though, in addition to gold six
now known,
other metals,
newcomers
—platinum,
than gold.
Osmium
rocks.
has a density of 13.1 ounces per cubic inch
is
far
behind.
point. Metals, generally, are lower-melting than
Rocks melt,
C. This
and mercury,
Three of these
osmium, and iridium— are denser, even,
and the other two are not
One more
are denser than lead.
in general, at temperatures of 1800
most
to 2000
high enough to allow rocky materials to be used to con-
struct furnaces
and chimneys. Here
in
Table 35 are the melting
points of the seven ancient metals:
Table 35 Metal
Melting Point (° C.)
Iron
1535 1083
Copper Gold
1063
Silver
961
Lead Tin Mercury
327 232
-39
Iron has quite a high melting point for a metal, which
the reasons crack.
it
was a hard nut, metallurgically,
Copper,
silver,
look at lead and
Lead and ture of the
and gold are
is
will
but
melt in any ordinary flame, and a mix-
melt at lower temperatures than either
"solder." It can
be
C. Such an alloy of
easily melted,
poured onto the
between two pieces of metal, and allowed to
Tin containing
for the ancients to
in the intermediate range,
separately— temperatures as low as 183
and lead
one of
tin.
tin are easy to
two
is
a little lead
is
tin
joint
freeze.
"pewter." Kings and nabobs used
gold and silver plates to eat from, despite their expense and
diffi-
THE FIRST METAL
163
culty of working, out of a sense of conspicuous consumption.
Poor people used clay and wood, which were
ugly. In
between,
there were pewter dishes. It
was particularly easy to work either
there is
is
a tale to
tell
tin or lead into tubes,
and
about each. Ordinary metallic "white tin"
stable only at relatively
warm
begins to be a tendency for
it
temperatures. In winter cold there
crumbly nonmetallic
to turn into a
"gray tin." This takes place slowly unless temperatures consider-
ably below zero are reached.
A
cathedral at St. Petersburg, Russia, installed a magnificent
organ with beautiful tin pipes. pipes disintegrated. That's
and gray
tin
tin,
but
I
Came
how
a cold, cold winter
and the
chemists discovered about white
doubt that the cathedral personnel were
particularly overjoyed at their contribution to scientific knowledge. It is all
very well to build organ pipes out of tin, but for ordinary
plebeian water pipes, tin was too expensive.
The
other low-melting
Roman Empire where city of Rome itself, for
metal, lead, was used. In those parts of the a central water supply was set
up
instance), lead pipes were used.
the fellow
who
it
And now you know why we
call
deals with water pipes a "plumber," even though
the pipes are no longer
As
(in the
made
happens, and as the
of lead.
Romans
did not know, lead com-
pounds are strongly and cumulatively poisonous. Under conditions, small quantities of the lead pipe
the water supply would
would
become dangerous over
certain
dissolve
and
longish periods.
There are even some who have recently suggested that the
Roman Empire ernment and
fell,
in part at least, because
social leadership in the city of
from "plumbism," that
But neither
silver
is,
tion
I
men
nor lead
is
the lowest-melting of the seven is still
held today) by
that brings us back one step in the chain of rumina-
described at the start of this chapter.
Mercury
of the gov-
were suffering
from chronic lead poisoning.
ancient metals. That record was held (and
mercury— and
key
Rome
will
be the subject of the next chapter.
THE SEVENTH METAL
12
It is
very difficult for an ivory-tower chemist such as myself to dem-
onstrate competence in the practical aspects of the science. Consequently,
always with a sinking heart that
it is
me
approaching
I
watch anyone
with a down-to-earth problem in chemistry.
It
always ends in a personal humiliation.
Well, not always.
Once, wife to
my I
in the days
came
to
me
wedding
I
was working toward
"Something," she
I was had time
still
in
my
my
me
She handed yet
it
waited and
me
but
I
had
incompetence many times
was her gold wedding
I felt,
said, "I
"But
the ring and, indeed,
it
do
so again.
that's impossible!"
had the appearance of
ring, inscription
uneasily, that she suspected
ring of low-grade gold. I
my
censoriously, "It's turned into silver."
stared at her with astonishment.
silver,
Ph.D.,
"What happened?"
She eyed I
my
"has happened
early stages as a chemist,
to demonstrate
over. I didn't enjoy the prospect of having to I said,
said,
ring."
winced.
already
when
in alarm.
Yet
I
and
all.
She
had bought her a
could think of nothing!
just can't explain this.
nothing in the world—"
I
Except for mercury,
there's
THE SEVENTH METAL "Mercury?" she
"How
with rising inflection.
said,
l6$
know
did you
about the mercury?" I
had apparently
magic word.
said the
happened. Inflating
my
I
saw instantly what had
chest and putting on an air of lofty con-
"To the
chemist's eye,
sideration,
I said,
vious that
what one has here
dear,
it is
amalgam and
gold
is
my
at once ob-
that you've
been handling mercury without removing your wedding ring first."
That was
of course.
it,
At the laboratory
mercury and was fascinated by it
so
it
I
brought
amuse myself with now and then.
to
fashion
couldn't resist pouring a drop into the
could play with
rapidly mixes with gold to
Yet despite
this sadly
mercury's fascination, cient
man
palm of her hand ring
silvery gold
so she
on and mercury
amalgam.
dramatic and highly personal instance of discussed the seven metals
known
to an-
in the preceding chapter with hardly a word for the
them— mercury. But
most unusual of merely saving
Mercury
I
form a
a small vial of
around in enticing
wife found the vial and
But she kept her wedding
it.
had had access to
home
(It rolls
My
and doesn't wet anything.)
I
is
it
for a chapter of
its
that wasn't neglect;
riddled with exceptional characteristics.
for instance, that
it
was the
strongly suspect that
it
was
I
own. I
am
sure,
least familiar of the seven metals
was the seventh metal (and the
and
last)
to
be discovered by the ancients.
As
for its
being the least familiar,
has to say about
it, if
written by people
only because
who had
little
or
we might
it is
no
a long
see
what the Bible
and
intricate
interest in science. It
book might
therefore be considered the authentic voice of the ancient nonscientist.
Gold, of course, all,
is
the standard of excellence and perfection to
even to the Biblical writers.
gold
is
to give
it
To
say something
is
more than
the highest possible worldly praise. Thus:
THE SOLAR SYSTEM AND BACK
l66
Psalms 119:127. Therefore I love thy commandments above gold; yea, above fine gold.
And
what do the
as nonscientists,
Biblical writers say
about
the other metals? For economy's sake, I've searched for a verse
many
that mentions as
Ezekiel
quoting
is
metals as possible, and here's one where
God
among
threatening the sinners
as
the
Jews:
Ezekiel 22:20. lead,
to
it,
and
The
and
As they gather
and
silver,
brass,
and
iron,
and
the midst of the furnace to blow the fire upon so will I gather you in mine anger and in my fury,
tin, into
melt
it;
you
I will leave
there,
and melt you.
compared to the various metals, notably
sinners are
ex-
cluding gold, to show that they are imperfect.
Here, by the way, of the
and
we must remember
that the English words
King James version are translations of the
may be
mistranslations.
was used indiscriminately
and
loy of copper
tin.
all
al-
version invariably trans-
an alloy of copper and zinc and
is
The
not what the Biblical writers meant. sion replaces
Hebrew
pure copper and for bronze, an
The King James
which
lates it as "brass,"
for
original
The Hebrew word nehosheth
is
Revised Standard Ver-
the "brass" in the King James with "bronze" or
"copper." If
we
substitute copper for brass in the verse
will see that I
to
mention
tin,
and
have managed, by using merely two Biblical of the ancient metals: gold,
six
lead.
from Ezekiel, you
That
leaves only mercury.
silver,
What
verses,
copper, iron,
does the Bible say
about mercury?
The answer is: Nothing! Not a word! Not in the Old Testament, Apocrypha.
It
was the most
seems clear that of
or the
New,
or the
the seven metals, mercury
exotic, the least used for everyday purposes,
most nearly what we would today
The
all
nonscientists
who wrote
call
the
a "laboratory curiosity."
the Bible were so
little
acquainted
THE SEVENTH METAL with
it,
they never had reason to mention
167
even in figures of
it,
speech.
As to
to
me
why
to
should be the
it
be no mystery.
across
comparatively
It is
and gold are
metals, only silver
be discovered; that seems
last to
less
rare, for of
the seven
common. Nor does one come
mercury ingots, naturally, since
it
liquid at ordinary
is
temperatures.
What
led to
its
discovery was the accident that
tant ore was brightly colored. This ore ically speaking, is
sulfur. It
When
mercuric
sulfide, a
is
its
one impor-
"cinnabar," which, chem-
compound
of mercury
and
has a bright red color and can be used as a pigment.
so used,
it is
word
also applied to its
in considerable
demand and, unwhen it was acci-
called vermilion, a
color.
Cinnabar must have been
doubtedly, there must have been occasions dentally heated to the point where
of metallic mercury. There that mercury was b.c.
known
is
it
broke up and liberated drops
evidence in the Egyptian tombs
in that land at least as far
This sounds ancient enough but compare
back as 1500 with copper,
it
and gold, which date back to 4000 b.c. Even after mercury had been isolated, there seems
silver,
new and may have made it too
difficulty in recognizing it as a
that
it
was liquid
to have
separate metal. different
metals to put on a par with them. Perhaps
it
been
The
fact
from the other
was only one of
the other metals in molten form. It
had the look of
ver? Silver to a
itself,
silver
about
ordinary solid
it.
Could
silver,
it
be, then, liquid
could be melted
good red heat, but mercury was a liquid
temperatures.
To
silver,
sil-
raised
ordinary
the ancient workers, such a difference was per-
haps not as significant as hot liquid
silver at
if
why not
it
would be
to us. If there could
be a
a cold one?
In any case, whatever the thought processes of the early discoverers of mercury,
it
remains true that mercury was the only
one of the seven metals not given a name of
its
own. Aristotle
THE SOLAR SYSTEM AND BACK
l68 called
it
and
"liquid silver" (in Greek),
physician Dioscorides called
The
the same thing.
came hydrargyrum
it
in
Roman
"water-silver,"
times the Greek
which
essentially
is
name is hydrargyros in Greek and beLatin. And in fact, the chemical symbol
latter
in
for mercury remains
Hg,
honor of that Latin name,
in
to this
day.
The Roman
writer Pliny called
The
"living silver."
reason for this
and motionless (that
moved under
is,
it
is
argentum vivum, meaning
that ordinary silver was solid
"dead") whereas mercury quivered and
slight impulse. If a
drop
fell,
it
shivered,
and the
away in all directions. It was "alive." An old English word for alive was "quick." We still use it with that meaning in the old phrase "the quick and the dead." We still droplets darted
say that vegetation "quickens" in the spring. If
outermost dead callus of the neath,
we
we
cut past the
skin, to the soft, sensitive tissue be-
"cut to the quick."
Naturally, "quick" characteristics of
comes
there are forms of
to
be applied to the more notable
one of which
life,
is
rapid motion.
To be
sure,
such as oysters, sponges, and mosses, which
life,
commonThey knew the dis-
don't show notable motions, but the language-making
no such
alty indulged in
tinction
"quick"
side-issues.
between a race horse and a hobbyhorse. Consequently,
came
to
mean
Nowadays, that thing
fine
else,
and
last
"rapid."
meaning of "quick" has drowned out
the older
meaning
every-
remains only in the old cliches
that never die and that remain to puzzle innocents.
would imagine that "the quick and the dead"
(Moderns
refers to
Los An-
geles pedestrians.)
Keeping can be
all this
in
mind, we see why Pliny's argentum vivum
literally translated as "quicksilver,"
old English
Where,
name
for
then, did the
The medieval
and that
is,
indeed, the
it.
name "mercury" come from?
alchemists approached
their
oughly mystical manner. Since most of them
work (not
a
thor-
all!)
were
in
THE SEVENTH METAL
169
incompetent, they could best mask their shortcomings by indulg-
What
ing in windy mysteries.
the public could not understand,
they could not see through. Naturally, then, alchemists favored metaphorical speech. There
were seven different metals and there were also seven different planets,
and
surely this could not
be coincidence, could
not, then, impressively speak of the planets
it?
Why
when you meant
the
metals?
Thus, the four brightest of the planets, in order of decreasing brightness, were the Sun, the
match these with
Moon, Venus, and and
gold, silver, copper,
Jupiter.
Why not
tin respectively, since
these were the four most valuable metals in order of decreasing value?
As
for the
others— Mars, the ruddy planet of the war god,
naturally iron, the metal out of
(As a matter of iron rust in
To
wonder
you carefully
else,
you can
select
matched
to the
sort of coincidence that causes
mod-
"there might not be something in
is
bound
to
al-
make words now and then and
out the words and don't touch anything
convince yourself that nonsense
easily
The slow-moving ness.
if
Mars may be due
counter that, one need only say that any random
succession of syllables if
which war weapons are made.
the ruddiness of
its soil. It's this
ern mystics to
chemy."
fact,
is
Saturn, slowest of
all
is
the planets,
to lead, the proverbial standard for dullness
sense.) is
naturally
and
heavi-
Mercury, on the other hand, which swings rapidly from one
side of the
Sun
to the other,
is
equated with the darting droplets
of quicksilver. (Thus, the seventh metal
enth planet. See Chapter
Some
of these
old-fashioned
i.
comparisons
names
is
matched with the
sev-
Pure coincidence!)
for certain
still
hang on
compounds.
in
the
form of
Silver nitrate, for in-
stance, appears in old books as "lunar caustic" because of the sup-
posed relationship of
compounds used
as
silver
and the Moon. Again, colored iron
pigments are sometimes called by such names
THE SOLAR SYSTEM AND BACK
17O
"Mars yellow" or "Mars
as
red."
Lead poisoning was once
referred
to as "saturnine poisoning."
The
only planet to enter the realm of modern chemistry in a
way was Mercury.
respectable
It
became the name of the metal, came about because
ousting the older quicksilver. Perhaps this
chemists recognized
name and
that
quicksilver
was not an independent
that mercury was not merely silver that was liquid or
quick.
Oddly enough, metals were named for planets in modern times, too, and the modern names stuck, of course. In 1781, the planet Uranus was discovered, and in 1789, when the German chemist Martin Heinrich Klaproth discovered a new metal, he named for the
new
planet and
it
became "uranium." Then,
when two metals were found beyond uranium,
it
in the 1940s,
they were
named
two planets, Neptune and Pluto, that had been found beyond
for
Uranus.
The new
Even the two
metals became "neptunium" and "plutonium."
asteroids got their chance. In 1801
and
and 1802, the
first
were discovered (see Chapter 4). Klaproth discovered another new metal in 1803 and promptly asteroids, Ceres
Pallas,
named it "cerium." The same year, an English chemist, William Hyde Wollaston, discovered a new metal and named it "palladium."
Mercury gained unusual
distinctions during the
Middle Ages.
Throughout ancient and medieval times, the chief source of mercury was Spain, and the Moorish kings of the land made spectacular
use of
it.
Abd ar-Rahman
III,
the greatest of them, built a
palace near Cordova about 950, in the courtyard of which a
fountain of mercury played continuously. Another king was sup-
posed to have slept on a mattress that floated in a pool of mercury.
Mercury gained another medieval stract nature. It
val alchemists
distinction
of a
more
ab-
seems that one of the chief aims of most medie-
was the conversion of an inexpensive metal
like
lead to an expensive one like gold.
That
this
could be done seemed likely from the old Greek no-
THE SEVENTH METAL tion that all matter
was made up of combinations of four basic
substances, or "elements/' which were called "air,"
and
we
stances
"fire,"
These were not
bad guess
The medieval ever. It
"water,"
common
sub-
by those names, but were abstractions which might
call
really a
"earth,"
identical with the
better be translated as "solid," "liquid," "gas,"
not
171
and "energy."
It
was
for the times.
alchemists went beyond the Greek notions, how-
seemed to them that metals were so
different
from the
ordinary "earthy" substances, like rocks, that there must be a particular metallic principle involved.
"earth," ciple,
made
This metallic principle, plus
a metal. If one could but locate the metallic prin-
one could add "earth"
in different
ways to form any metal,
including gold. Naturally, solidity to it
then?
It
and produced a
principle,
What
solid metal.
was a liquid and that must be because
"earth" in
some
by adding "earth" to the metallic
it.
Perhaps what
little it
about mercury, so little
itself.
began to work with mercury indefatigably, and
since mercury vapors are cumulatively poisonous,
many
had
it
did have could be removed in
fashion, leaving the metallic principle
Many alchemists
one added
wonder how
I
them died prematurely. The vapors affect the mind, too, but I suppose it's hard to tell when an alchemist is speaking real gibberish. For that matter, I wonder about that Moorish king who slept over a pool of mercury. How did he feel as the months of
wore on?
Some alchemists must have reasoned unique among metals for its yellow color; added
to
mercury
usual in that, unlike other earths, terious blue flame
seemed easy to
therefore,
(itself silvery in color) is
obvious candidate for a yellow "earth"
It
further that gold
it
is
was
what must be
a yellow "earth."
The
sulfur. Sulfur was un-
could burn, producing a mys-
and an even more mysterious choking odor.
seize
on the idea that mercury and
sulfur repre-
sented the principles of metallicity and inflammability respectively.
The combination
of the
two would therefore put
fire
and
THE SOLAR SYSTEM AND BACK
172
mercury and turn
solidity into
from a
it
silvery liquid to a
golden
solid.
To be
sure,
mercury and sulfur did combine— to form cinnabar.
This was a perfectly ordinary red "earth," nothing the dullness of fact was
rarely
but
like gold,
allowed to spoil the glorious
alchemical vision.
These medieval theories slowly died eenth century, when
During that century, the
fancy.
principle received a cruel it
would have to be
The
in the course of the eight-
chemistry passed through
real
role of
lusty in-
its
mercury as a metallic
knock on the head. As such a principle but was
a perpetual liquid,
it?
year 1759 was a very cold one in St. Petersburg, Russia, and
on Christmas day there was a blizzard and the mercury sank very low
in
the thermometers.
Lomonosov
silievich
tried
The Russian chemist Mikhail Vasto get the temperature to
drop
still
lower by packing the thermometer in a mixture of nitric acid and
The mercury column dropped no lower. It had frozen! The world, snow.
— 39
to
C. and would drop
for the first time,
saw
solid
mercury, a metal like other metals.
By
that time, though, mercury had gained a
outweighed
its false
value was based
A
This
role as a metallic principle. In a way, this
upon
is
its
density,
which
new
13.6 times that of water.
is
13^
pounds.
an amazingly high density. Not only would
in mercury, lead
a liquid; too
would do
much
it
Somehow we
is
is
with water. Thus, when
brought face to face with his
it
up and put
and automatically
gives
it
it
somewhere, he
the kind of
give a jug of water of corresponding size.
And
cury acts as though
table.
it
steel float
don't expect this of
he can be spectacularly astonished.
asked, casually, to pick
hand around
so.
of our experience
young chemistry student
sizable jug of mercury, is
value that far
pint of water weighs roughly a pound; a pint of mercury would
weigh about
a
new
were nailed to the
lift
first
If
he
puts his
he would
of course the mer-
THE SEVENTH METAL
173
made
In 1643, the Italian physicist Evangelista Torricelli of mercury's density.
He
pump
a
level.
could only
He
lift
was puzzling over the problem that a
column
of water 34 feet above
reasoned that the actual work
34 feet high exerted a pressure at
its
A
A
known.
liquid
made
much
a clumsy
is
use of mercury, the densest
column of mercury (13.6 times
water) would produce as
full pres-
no higher.
check that more conveniently (a 34-foot column
thing to handle), Torricelli
column
column of water
base equal to the
sure of the air so the water could be raised
natural
its
of raising that
was done by the pressure of the atmosphere.
To
use
pressure at
dense as
as
base as a column
its
of water 13.6 times as high. If 34 feet of water balanced the total
then 2.5 feet (or 30 inches) would also balance
air pressure,
Torricelli therefore filled a yard-long tube
upended
bowl of mercury. The mercury began pouring out,
in a
it
but only so
far.
to 30 inches,
it
When
the height of the column had decreased
then stayed put, balanced by the
had demonstrated cury entered a
his point
new
and had invented the barometer. Mer-
if
the
air
at Earth's surface,
were as dense
we could
of the atmosphere would be.
the surface
air.
10,560 times
grows
numerous
instru-
its
air,
less
all
the
easily calculate
Mercury
is
way upward
as
what the height
10,560 times as dense as
Therefore, a column of mercury would balance
own
height of
mercury would balance
The
Torricelli
science.
Incidentally, it is
air.
career as a unique substance (a very dense,
electricity-conducting liquid) adapted to use in
ments of
it.
with mercury and
however,
dense as
is
we
5
air.
miles of
This means that 30 inches of air.
not evenly dense rise
and therefore
all
the
bellies
way upward. upward
It
to great
heights.
Of est
all
the metals
melting point.
nary temperatures.
known
It
to the ancients,
mercury had the low-
was the only metal to remain liquid at
ordi-
4
THE SOLAR SYSTEM AND BACK
174
Since ancient times, chemists have discovered dozens of metals, but cury. It
new
none can shake the record low melting point of mer-
was and remains champion.
A
number
of the metals dis-
covered in modern times, however, melt at the temperature of
melting lead or
less.
Here
in
Table 36
is
the
list:
Table 36 Metal
Melting Point
-39 +28
Mercury Cesium Gallium Rubidium
30 38 62
Potassium
Sodium Indium
97 156
Lithium Tin Bismuth Thallium
186
232 271 302
Cadmium
321
Terbium Lead
3 27 327
There you are— the fourteen lowest-melting metals. Five of the eight lowest are the "alkali metals," which, in order of increasing
atomic weight, are lithium, sodium, potassium, rubidium, and cesium. Notice that the melting points are 186, 97, 62, 38, and 28 respectively.
The
melting point goes
down
as the
atomic weight
goes up.
The melting
point of cesium
(for stable metals
F. This
to 82
of a
cury
day
summer
A
second only to that of mercury
temperature of 28
means that cesium would be
day's heat,
and cesium
Could we play with cesium hot enough?
is.
is
anyway).
is
as
is
C.
is
equivalent
liquid at the height
twice as
common
as mer-
we play with mercury
if
the
THE SEVENTH METAL Not
the alkali metals are extremely active and
likely. All
act violently with,
come will
in contact
among
with the perspiration film on your hands and you alkali
increasing atomic weight, cesium
No
There still
is
metals grow more active with the worst of the lot that I've
playing with cesium!
is
a sixth alkali metal, francium, with an atomic weight
higher than that of cesium.
It
its
not known.
would be
It
and the
C. (73
New
be liquid through most of a
However, combine
chemical prop-
and
F.)
would
it
York summer.
chemical activity with
its
fact that only a
its
safe to predict, however, that
melting point would be about 23
therefore
been
radioactive, has only
is
prepared in excessively minute quantities, and erties are
re-
other things, water. Let the alkali metals
be sorry indeed. Since the
listed.
175
its
radioactivity,
few atoms at a time can be brought
to-
gether—and forget francium. Metals can be mixed to form erally
and such mixed metals gen-
alloys,
have a lower melting point than any of the pure metals
making
it
up.
Suppose, for instance, parts of lead, solidify.
The
1
of tin,
result
is
we melt and
1
of
together 4 parts of bismuth, 2
cadmium, and
of the alloy melts at a temperature lower than 23
melts at 71 ° C.
It is a "fusible alloy,"
and tin low as 60 ° C.
is
the mixture
raised slightly, will
2 °
C,
the alloy
one that melts below the
boiling point of water. Lipowitz's alloy, in of lead
let
"Wood's metal." While no component metal
which the proportion
melt at temperatures as
Fusible alloys have their chief uses as safety plugs in boilers or
automatic sprinklers.
The
recipe can
be adjusted to give them a
melting point slightly above the boiling point of water. high
rise in
from the
A
too-
temperature melts them and allows steam to escape
boiler, relieving
dangerous pressure, or allows water to
pass through the automatic sprinklers.
Fusible alloys are also used in practical jokes.
A
teaspoon
made
THE SOLAR SYSTEM AND BACK
176
Wood's metal
of his
is
passed to someone
who then
innocently
hot coffee while carrying on an animated conversation.
connoisseurs of such things, the look on the victim's face finds himself holding the is
mere stub
stirs
To
when he
of the handle of the spoon,
supposed to be delectable indeed.
You can
also
form
alloys of the alkali metals
at lower temperatures than will, in
some
cases,
any
alkali
which would melt
metal alone— and which
melt at temperatures lower, even, than that of
mercury.
But suppose we confine ourselves with impunity.
The
alkali
to solid metals
we can handle
metals and their alloys cannot be
touched. Neither can solid mercury, which
is
too cold for comfort.
Let us ask what metals among those that can be touched are most easily melted.
There are the
fusible alloys of
melting than any of them
and melting
And now its
at only 30
that
I
have
is
which
I've just spoken,
gallium— a pure metal,
but lower
safe to touch,
C. finally
story— in the next chapter.
reached
it, I
intend to go on with
13
I
THE PREDICTED METAL
frequently receive letters from readers
some kind
facts into
of pattern.
who attempt
to find
some
by
shuffling facts or supposed
Very
often, the readers are not
insight into the mysteries of nature
professionals or experts in the subject they are trying to handle.
My own but
I
impulse, then,
never quite dare.
even when
I
is
to reject such attempts out of
invariably
all,
peculiar horror against going
man who
is
Reina Newlands, and if I
all
wrong,
one can never
down
I
try to
tell;
make my
and
I
have a the
in scientific history as
laughed at So-and-So.
For instance, there
him
ponder before answering, and
decide they are
I finally
response a polite one. After
hand-
only
knew
I
his
Newlands was born
the
man who
laughed at John Alexander
would gladly point the
finger of scorn at
name.
in 1837 of
an English father and an
Italian
mother, and he remembered his Italian ancestry well enough to fight
with Garibaldi in i860 for the unification of
interested in both chemistry
Italy.
He
was
and music, and eventually became
an industrial chemist specializing
in sugar refining. In his spare
moments, he turned
from sugar
his attention
to the elements.
THE SOLAR SYSTEM AND BACK
178
One had
to
wonder about the elements
sixty different
elements were
sorts,
and
There seemed no
no
order.
varieties.
in those days.
known— elements
about
logic to the
of
list,
By all
1864, kinds,
however,
There seemed no way of predicting how many elements
there might be altogether
the number might be
and
infinite.
all
in 1864,
Chemists were growing more and
more depressed over the matter. elements of
anyone could say
for all
there were vast
If
numbers of
would be unbearably com-
kinds, the universe
plicated. It is
almost an article of faith with scientists that the universe
orderly and, basically, simple. Therefore, there
had
to be
is
some
way of finding order and simplicity in the list of elements. But how? Newlands amused himself by juggling the elements in various ways. Over the past few decades, chemists had been carefully working out the atomic weights of the elements (that tive
is,
the
masses of their respective atoms), and those figures
seemed hard and reasonably accurate.
Why
rela-
now
not, then, arrange the
elements in the order of atomic weight?
Newlands did
so,
then
listed
them
in a table seven elements in
width. First, there were the seven elements of lowest atomic weight; then, under them, the next seven, and so on. It seemed to
Newlands that
certain groups of elements of very similar prop-
erties fell in vertical lines
when
this
was done, and that
this
was
significant.
Could
it
be that elemental properties repeated themselves
groups of seven? His musical interests led him
member
in
irresistibly to re-
that the notes of the scale repeated themselves in groups
of seven.
The
the
Musical notes repeated themselves in octaves, in other
first.
eighth note ("octave") was almost a duplicate of
words. Might not the same be true of the elements?
Newlands therefore wrote up his results in a paper presented Chemical Society and referred to
for publication to the English his discovery as the
"Law
of Octaves."
THE PREDICTED METAL The might
mine
society rejected
179
with contempt, very
it
much
for similar publication.
jection, though, for
had
it
They had some
they
as
had submitted one of these speculative science
if I
essays of
reason for the
re-
to be admitted that Newlands's table
was quite imperfect. Although some very similar elements
into
fell
columns, some extraordinarily dissimilar elements did the same.
However, what
really
bothered the society,
I
am
sure,
was the
whole notion of playing games with elements and making tabular arrangements.
The
very notion of listing the elements in order of
atomic weight seemed a wise guy
why he see
I
trivial trick,
and one chemist
(this
referred to at the start of the essay) asked
didn't try to
what kind of a
list
the
is
Newlands
the elements in alphabetical order and
table he could squeeze out of that.
I
only hope
the gentleman lived long enough to have to swallow his words. It
would only have taken eleven Actually,
a
two years
earlier
years.
(and quite unknown to Newlands)
French geologist with the formidable name of Alexandre Emile
Beguyer de Chancourtois had also
tried to list the
elements in
order of atomic weight. Instead of making a table, he imagined
the ner,
list
of elements
wound
helically
he got much the same
table,
results
about a cylinder. In
man-
this
Newlands had obtained
in his
but in nowhere nearly as simple a manner.
Beguyer wrote a paper on the subject and included a painstaking diagram of what his cylinder of elements would look
like.
The
paper was published in 1862 but the complicated diagram was omitted.
The
omission of the diagram
to follow. This
was
all
made
the article impossible
the more so since Beguyer de Chancourtois
was a poor writer who made
free use of geological terms that
were
unfamiliar to chemists. His paper was completely ignored.
Despite the dangerous possibility of being laughed
at,
chemists
continued, occasionally, to try to wring order out of the elements. As the
list
of
1860s closed, two men, independently, each
THE SOLAR SYSTEM AND BACK
l80
One was
a German named Julius Lothar Meyer and named Dmitri Ivanovich Mendeleev. Matters had grown more subtle in the five years since Newlands. Both the German and the Russian arranged elements in
made
a try.
the other a Russian
order of atomic weight, but both used other atomic properties as
Without going
additional guides.
into detail here,
I
can say that
Meyer made use of atomic volume and Mendeleev used valence. Each man noted that when the elements were arranged in order of atomic weight, the other properties (such as atomic volume and valence) rose and fell in an orderly manner. They recognized further that the period of rise
and
same number of elements. At the seven elements long, but later lands's errors that able,
he
tried to
and that helped make
would
fall
into the
it
fall
did not always involve the
start of the list
grew longer.
make the
It
the period was
was one of New-
length of the period invari-
inevitable that dissimilar elements
it
same column.
Both Meyer and Mendeleev succeeded
Mendeleev managed
to get into print
in publishing their work. first,
One might
while Meyer published in 1870.
publishing in 1869,
expect that Mendeleev,
a Russian, would lose out even so because, in general, European
chemists did not read Russian, and Russian discoveries were usually
ignored in consequence. However, Mendeleev was foresighted
enough to publish
Even credit,
so,
were
in
German.
Mendeleev and Meyer might it
still
have received joint
not for the difference in their approaches. Meyer
was timid. Not
at all eager to
compromise
his scientific career
by
stepping out too far ahead of the front lines, he advanced his conclusions in the form of a graph relating atomic volume to
atomic weight.
He made
graph speak for
itself,
no attempt
which
it
at interpretation,
but
let
the
did but softly.
Mendeleev, however, actually prepared a "periodic table of the elements" as Newlands had done, one in which the various properties varied in a periodic
manner. Unlike Newlands, Mendeleev
refused to allow any of the columns to contain unfitting ele-
THE PREDICTED METAL ments. didn't
If fit,
an element seemed about to
Mendeleev moved
it
fall
into a
l8l
column which
to the next column, leaving
it
behind
an empty hole.
How that
it
explain the
empty hole? Mendeleev pointed out boldly
was quite obvious that not
all
elements had yet been
dis-
covered and the empty hole contained one of these undiscovered elements. Newlands had
made no allowance
undiscovered
for
elements. As for Meyer, his graph was so arranged that "holes"
did not stand out, and
Meyer himself
later
admitted he would
never have had the courage to argue as Mendeleev had done.
From
the properties of the remaining elements in the column
with the empty hole, Mendeleev went on to
insist
he could even
predict the properties of the undiscovered elements. in particular, the holes that
He
selected,
were under the elements aluminum,
boron, and silicon in his early tables. These holes, he said, contained undiscovered elements which he provisionally
aluminum," "eka-boron," and
(Eka the
is
"first
Sanskrit
named
"eka-silicon" respectively.
the Sanskrit word for "one" so that the
name
implies
element under aluminum" and so on. Since dvi
word
for "two," the
I
know
is
the
two holes under manganese would
be "eka-manganese" and "dvi-manganese" the only cases
"eka-
respectively.
These are
of where Sanskrit has been used in scientific
terminology.)
Consider eka-aluminum, for instance. Judging from the the column and from
decided that
its
its
position in the
list
generally,
atomic weight would be about 68; that
have a moderate density of
rest of
Mendeleev
5.9 times that of water; that
it
would
it
would
have a low melting point but a high boiling point; and that
would have
The
it
a variety of carefully specified chemical properties.
rest of
the chemical world reacted to this with anything
from a laugh of indulgent amusement to a snort of contempt. Playing with elements, and building complicated structures out of them, was bad enough, but describing elements one had never
THE SOLAR SYSTEM AND BACK
l82
seen on the basis of such structures seemed like nothing
more
than mysticism—or even charlatanry.
Mendeleev might not have been saved from worse fact that he was Russian. Westerners must have felt indulgent toward the ravings of mystical Russians, and tolerated there what they would not have tolerated among their own I
wonder
criticism
if
by the
countrymen.
But
the focus to France again and to another French-
let's shift
man with a formidable name—Paul Emile Lecoq He was a self-educated young man of means,
de Boisbaudran. fascinated with
chemical analysis, and particularly attracted by the new technique of spectroscopic analysis in to
which heated minerals could be made
produce spectra composed of
Each element produced
its
lines of differently colored light.
own
spectral lines distinct to itself.
This technique had been introduced in 1859 an d
had almost
at
its
once found minerals yielding spectral
developers lines
not
produced by any known elements. Orthodox chemical investigation into the minerals producing these lines demonstrated the
existence of two
new
elements: cesium and rubidium.
Lecoq de Boisbaudran burned to discover elements, too, and moving into the field at the first announcement, he spent fifteen years subjecting every mineral
troscopic analysis.
and moved
his
hands on to spec-
carefully considered the lines
he obtained
intelligently in the direction of those minerals
him
most
new elements he wanted. he chanced upon a mineral which had been known
apt to give Finally
He
he could get
the
early mineralogists as galena inanis or "useless lead ore." It useless because
it
was a mixture of zinc
sulfide
and procedures designed to get out the lead naturally failed. It
is
now
called "sphalerite"
meaning "treacherous" because
it
so
and it
from
to
was
iron sulfide
didn't contain a
Greek word
often deceived the early
miners.
This ore was anything but useless or treacherous to Lecoq de Boisbaudran, however. In February, 1874, he subjected the min-
THE PREDICTED METAL and spotted two
eral to spectroscopic analysis
183
he had never
lines
seen before.
He
hastened to Paris where he repeated his experiments before
important chemists and established his
priority.
He
then began
working with larger quantities of the mineral and by November, 1875,
worked
some
to the
on the
tests
it down to a gram of a new metal, enough to present Academy of Sciences in Paris and to run chemical
rest.
The new metal proved had a density of
70. It
point of 30
showed a
C,
to
have an atomic weight
just
under
5.94 times that of water, a low melting
C, and
a high boiling point of nearly 2000
it
variety of specific chemical reactions.
This had no sooner been announced when Mendeleev, far
away
pointed out excitedly that what Lecoq de Bois-
in Russia,
baudran was describing was precisely the eka-aluminum that he
had deduced from
The
his periodic table five years before.
chemical world was thunderstruck. Mendeleev's predic-
tion of the properties of
eka-aluminum existed
in print.
The two
existed in print.
There was no denying riodic table ity
had
tallied it.
Lecoq de
new element
Boisbaudran's description of the properties of his
almost exactly in every detail.*
Mendeleev had
to
be
right.
to be a useful description of the order
and
The
pe-
simplic-
behind the elements.
If there
was any doubt, the other two elements described by
Mendeleev were fallen
credit
death, just
found within a few years and predictions
also
with the fact. As all the ridicule had on Mendeleev before and none on Meyer, so now all the went to Mendeleev. In 1906, just a few months before his
were again found to
tally
Mendeleev almost received the Nobel
one vote to Moissan, the discoverer of
Prize, losing out
by
fluorine.
* Lecoq de Boisbaudran first got a figure of 4.7 for the density, but Mendeleev insisted that that could not be so. And he was right. The Frenchman's first samples were too impure. After proper purification, the density figure matched the prediction. discrepancy in which the prediction won out over the first observation made the situation even more dramatic.
A
THE SOLAR SYSTEM AND BACK
184
Both Newlands and Beguyer de Chancourtois
to
lived
see
themselves vindicated. After Beguyer de Chancourtois died in 1886, a French journal, in remorse, published his diagram of the
one that had not been published
cylinder, the
And
Royal Society
in 1887, the
paper which the Chemical Society had refused to publish.
for the
As
for the
element discovered by Lecoq de Boisbaudran, he took
the privilege of the discoverer and
named
ism, he
Rome and
it
Yet was
used the Latin
name
For
Out
it.
this
of noble patriot-
he turned
to ancient
Gallia ("Gaul" in English), so
"gallium."
patriotism, pure
it
named
for his native land.
new element became
that the
is
thirty years before.
gave Newlands a medal
finally
and unalloyed? Lecoq
"the cock," and that noble barnyard fowl
is
in English
gallus in Latin.
Well, then, was gallium named for Gallia, the nation, or for the discoverer himself?
Gallium hand,
is
it isn't
common
Who
common uncommon
not an extremely
element, but on the other
a particularly
one, either. It
as lead,
which makes
it
about
mercury and three thousand times gallium
nately,
much more
is
earth's crust than
make
Its richest
the ore
is
its
as
thirty times as
common
is
about as
common
as
as gold. Unfortu-
evenly spread out through the
any of these other elements, so that there are
few places indeed where tion to
gallus,
can say?
it
can be found in
sufficient concentra-
extraction practical.
source
is
a
mine
in
Southwest Africa and even there
only about 0.8 per cent gallium (as compared, though,
with a usual figure of 0.01 per cent). Several thousand pounds of
metal are
all
The most which
is
usually,
that
will
melting point
body (37
produced in the course of a
spectacular property of gallium
29.75
but
is
is
is
year.
its
melting point,
C. (or 85.55 F.). This means that it is solid melt on a hot summer day. Notice, too, that its
below the normal temperature of the
C. or 98.6
dramatic experiment.
F.). This
makes
it
human
possible to perform a
THE PREDICTED METAL You
185
begin with a rod of solid gallium. That's a moderately ex-
pensive proposition right there, for the present cost of gallium is
something
like
$50 an ounce.
Oh
you borrow a rod of
well,
solid gallium.
when
Naturally, you choose a day
and you hold the rod
seventies
the end of the gallium rod leave
it
down
into the
is
in the
Now
bring
palm of your hand and
there.
Slowly, the
The
the temperature
in a pair of cool tongs.
warmth
of your
hand
melt the gallium.
suffices to
rod shrinks, and gathering in your palm will be a puddle of a
silvery liquid that looks like
produce
and
this effect
it
that looks like steel puddle
Liquid gallium
is
No
mercury.
other pure metal will
quite creepy to watch something
is
up
in that
manner.
perfectly safe to hold, but
dense as mercury so
it
is less
than half as
doesn't have the latter element's unusual
weight. Furthermore, liquid gallium wets glass as mercury does not,
which deprives the former of some interesting
The
melting point of gallium can be lowered
still
effects.
further
if it is
mixed with other comparatively low-melting metals. With the proper admixture of indium and as
low as 10.8
tin,
an alloy with a melting point
C. (51.4° F.) can be produced.
It
can replace mer-
cury for frictionless electric contacts with moving parts.
Once if it is
gallium melts,
cooled quite a
However,
it
freezes again only with reluctance, even
a piece of solid gallium
if
even in an ice bath.
bit. It will stay liquid is
dropped into such "super-
cooled" liquid gallium, the solid acts as a "seed" about which the gallium atoms line up in orderly fashion, so that the liquid fies
solidi-
at once.
In the case of most substances, the liquid form
more voluminous than the ally shrinks
when
solid form.
it solidifies.
There are
A
dense and
liquid therefore gener-
several exceptions to this,
however, and the most important of them
Where
is less
liquid water has a density of 1.00
is
water.
gram per cubic
centi-
meter, ice has a density of 0.92 gram per cubic centimeter. This
THE SOLAR SYSTEM AND BACK
l86
means that 10 cubic inches of 11 cubic inches of ice.
The
back to 10 cubic inches
is
in
a
closely
fitting
enormous.
If
water
container,
sealed
must be exerted on the
ice to
keep
it
is
allowed to freeze
enormous pressure
that
from expanding. There are
few containers that can do so and even strong ones
Gallium
is
another exception.
The
means that 29 cubic inches of
The
as in the case of water,
gallium
is
will shatter.
density of the liquid
grams per cubic centimeter, while that of the cubic inches of solid.
form
liquid water will freeze to
pressure required to shrink that ice
solid
is
is
6.1
This
5.9.
liquid gallium will freeze to 30
pressures developed are not as
enormous
but they are large enough. For that reason,
shipped in flexible containers of rubber or
in the course of shipping, the metal melts
and
plastic. If,
resolidifies,
the
containers bulge and distort rather than break.
Gallium
is
remarkable not only for
its
low melting point, but
also for its high boiling point. It boils at 1983 °
nary temperatures, or even at a red heat, quantities of vapor. In this
which
boils at 357
it
is
it
C. so that at ordi-
produces insignificant
quite different from mercury,
C. and which produces sizable amounts of
vapor even at ordinary temperatures. Mercury vapor
is
toxic
which means that the metal should be handled with considerable care.
at
Gallium, on the other hand, poses no problems of that sort
all.
This combination of low melting point and high boiling point
on the part of gallium
Mercury
is
raises a point.
used in thermometers because
it is
liquid throughout
the ordinary range of temperatures in which chemists are interested.
To
record temperatures below
— 39
C. chemists have to
use alcohol thermometers, for ethyl alcohol doesn't freeze
temperature of
— 117
C.
is
reached. For temperatures lower
till
a
still,
other dodges are used.
What
about temperatures in the ranges higher than a mercury
thermometer can handle? For that we need some substance that will
not change with heat (an element
is
safer
than a compound
THE PREDICTED METAL in this respect), that will
187
be liquid through part of the liquid
range of mercury and that will remain liquid at temperatures as
high as possible. In other words, what elements have melting points lower than
C. and boiling points higher than 357 C? There are exactly fourteen of them and I am going to arrange them in Table 37 in 357
order of decreasing length of temperature range over which they
remain liquid:
Table 37 Element
Melting Point (° C.)
Tin Gallium Indium Lead Bismuth Thallium Lithium Sodium
(degrees)
2270
2038
30
1983
156
2000
1953 1844
327 271
1560
1620
1293 1289
ii55
1457 1336 880
98 62
Rubidium Cesium
Range
232
302 186
Potassium
Liquid
Boiling
Point (° C.)
1150 782
700
698 662
670 688
642 47i
760
38 28
Selenium
217
Cadmium
321
767
446
Sulfur
113
445
332
As you
the elements listed have a liquid range
see, three of
nearly or quite 2000 degrees. This
no others sure, a
like it in
number
the entire
list
very unusual, for there are
of elements that remain liquid for 2000 degrees
and more, but that have
their liquid range in a very high
convenient spread of temperature. liquid for 2600 degrees useless.)
is
of elements. (There are, to be
from 2700
Osmium,
and
in-
for instance, remains
C. to 5300
C. That's pretty
THE SOLAR SYSTEM AND BACK
l88
For the "high, but useful" range, which would take us up to
C, we
2000
indium
As
have
just
the three elements:
tin,
gallium,
happens, none are elements that are available in large
it
quantity, but then large quantities are not needed for
Of
eters.
the three, gallium
far the easiest to filling
and
in that order.
is
thermom-
the lowest melting and therefore
handle in a technique that must use liquid in
the thermometer.
For that reason, gallium thermometers have indeed been used.
As the
column of mercury is enclosed by glass in the ordinary thermometer, so the fine column of liquid gallium is enclosed by fine
quartz in the gallium thermometer. Such gallium thermometers are particularly useful in the range
Gallium
is
from 6oo°
proving to be useful in
all sorts
which purpose
One
of
it
C.
of solid-state devices,
must be prepared (and concentrations of not more than one part in a for
to 1500
is)
with impurity
million.
compounds, gallium arsenide (GaAs), can be used
its
in
solar cells, converting sunlight directly into electrical current. It
can be used as a semiconductor and in transistors at temperatures
beyond those work. There laser
at
is
which more ordinary devices of that
every reason to think
it
sort will
can be used to produce a
beam.
There
no doubt but that gallium can make
is
splash in the
pens to
it is
manner
of
new world
likely to
its
a satisfactory
of far-out science, but nothing that hap-
outweigh the glamour and significance of the
discovery.
BIOLOGY
THE TERRIBLE LIZARDS
14
James D. Watson has recently published a book, The Double
which he
Helix, in
structure of the lines
details the inside story of the discovery of the
DNA
molecule.
The book
is
making the head-
not because of the importance of the subject but because of
the fact that
human Well,
it
exposes scientists as
human
failings.
why
not?
A
great intellect need not necessarily
panied by a great soul. There are
villains
among any other group. My own pet candidate for a high place Sir Richard Owen, a nineteenth-century was the
last of
These believed
in evolutionary
nal forces that drove creatures
When,
in
Species, in selection, it,
among
1859,
English zoologist.
who had
naturalist
horrified.
force,
is
He
taken
Lorenz Oken.
development through vague
Charles Darwin published
was a blind
as
inter-
on to some particular end.
which he presented evidence
Owen was
be accom-
scientists
in scientific villainy
the top-rank "nature philosophers"
up the mystical notion of the German
scribed
beings possessed of
The
for evolution
Origin
of
by natural
Natural selection, as Darwin de-
changing species through
on random variations among individuals.
its
action
THE SOLAR SYSTEM AND BACK
192
Owen
could not accept evolution by random effects and he
came out even his
against Darwin. That, of course, was his right. It was scientific
suggestion,
like
duty to disagree with scientific
all
battles fought in the intellectual arena,
was outlawed in such
No He
Owen
many
make those
chose to
tensively
and no honorable weapon
chose to review Darwin's Ori-
he could wangle.
different outlets as
reviews anonymously and to quote ex-
like a
He
crowd.
of the contents of the
own
his
book and
urged others to denounce Darwin,
to ridicule
vitriolically
them the
before lay audiences, feeding
work,
chose to give an unfair it
than to present opposing testimony objectively. Worst of
ically,
the
survive
to
and with worshipful approval from
making himself sound
summary
had
battles.
honorable weapon.
gin of Species in as
might. Darwin's
all his
suggestions,
and
rather all,
he
unscientif-
necessary misin-
formation for the purpose. In short, it is
Owen was
cowardly, spiteful, and contemptible, and
a source of gratification to
me
that he lost out.
Yet that can't be allowed to obscure the portant contributions to biology.
He
fact that
he made im-
discovered the parathyroid
glands in 1852, while dissecting a rhinoceros. (It was to be quite
some first
years before they were found in
to describe the recently extinct
man
moas
as well.)
of
New
He
was the
Zealand and
the anything but extinct (alas!) parasite that was later found to
be the cause of
trichinosis.
His greatest fame to the general public, however, word.
He
was one of the
earliest of
those
who
lies in
a single
studied the
fossils
of certain giant creatures, long since extinct, which soon caught
the imagination of the world. Weighing up to five times the size of the largest living elephant, they shook the ground between
70,000,000 and 270,000,000 years ago.
The huge
skeletons that were built
up out of the
nants were clearly reptilian in nature, so rible lizards,"
Owen
fossilized
rem-
them
"ter-
called
and since he used Greek, that became "Dinosauria."
THE TERRIBLE LIZARDS
193
more
closely related to
(Actually, those ancient giant reptiles are alligators
than to
lizards,
but
I
must admit that "Dinocrocodilia"
would have been a rotten name.)
The name caught
on,
and today,
am
I
sure,
many American
children can describe various dinosaurs even though they can't describe a hippopotamus
Yet
for all the
is
term
is
it
for all its continuing pop-
has passed out of the scientific picture. As
ularity, it
there
and never even heard of an okapi.
fame of the word, and
no
single
group of animals
we can
gone from the chart of animal
call
it
turns out,
by that name. The
classification.
You can
look
over from top to bottom and you will find nothing labeled
"Dinosauria." (Ha, ha, for you, Sir Richard Owen.)
Furthermore, dinosaurs are not necessarily large and monstrous.
Many
of
them were quite small and were considerably less an angry police dog. Then, too, some of the
rible" than, say,
"ter-
large
extinct reptiles that look terrible indeed are not considered dinosaurs in the strictest sense of the word.
So let's go into the matter of the terrible lizards and find out what they are and what they are not. In classifying ancient reptiles one must, of necessity, use bone structure as the source of distinctions, for
these long-dead creatures that
used quite often, because
it
we have
it is
only the bones of
left to study.
The
skull
has a complicated structure of
is
many
bones, and this structure appears in convenient broad variations.
For instance, the
class "Reptilia"
is
divided into
six subclasses
in accordance, to a large extent, with the structure of the skull.
The most
primitive skulls have the
bony
structure behind the
eye socket solidly enclosed. Such a skull belongs to the subclass
Anapsida ("no opening").* Greek apsis means "wheel/* "arch," "vault," and a few other meaning of "wheel," and consider that it might be applied to a roughly circular opening, we might as well translate the word as "opening" and make it clear. In this article, I will try to give the literal meanings of the zoological terms, which are almost always in Greek or Latin, of course. I must not conceal from you that I don't always know why those literal meanings have been chosen. If any Gentle Reader knows, I will welcome the * Actually, the
things. If
we
information.
take the
THE SOLAR SYSTEM AND BACK
194
The
earliest
skulls.
important
the order Cotylosauria ("cup-
reptiles, of
because of their cup-shaped vertebrae), had anapsid
lizards,"
These
feet long,
more than
cotylosaurs, low-slung, stocky, not
and not
terribly
forebears, existed about
advanced over
far
They
from which
all
forms branched off—
later
though the cotylosaurs themselves are long since
One
group of their descendants,
are often
stem of the
called the "stem-reptiles" since they represent the reptile family tree,
amphibian
their
300,000,000 years ago.
six
extinct.
who appeared
early (perhaps
230,000,000 years ago), and only one, retained the anapsid skull.
Oddly enough,
this primitive order
although more ad-
still exists,
vanced cousins have long since grown
This
extinct.
is
Chelonia ("turtle"), which, of course, includes the
the order
turtles
and
tortoises.
Another type of
reptilian skull has
socket. Creatures with such skulls sida
an opening behind the eye
make up
the suborder Synap-
("with opening"). This entire suborder
there are
no
living reptiles with synapsid
scended from these Synapsida are the
There are two other kinds of ing behind the eye sockets.
is
extinct; at least,
skulls.
mammals
However, de-
of today.
reptilian skulls with a single open-
The arrangement
of the bones around
that opening differ in the two cases, and both differ from the
arrangement in the synapsid Parapsida
("side opening")
Both of these suborders are reptiles
skulls.
So we have the suborders
and Euryapsida ("wide opening"). totally extinct.
with either paraptid or euryaptid
There are no
skulls.
living
Nor have any
non-reptilian forms been descended from them.
The most
familiar
("fish-lizards").
This
is
of
the
a good
parapsids
are
name because
appearance, 220,000,000 years ago or
so,
the
Ichthyosauria
at their
first
known
they had already been
become completely adapted to it. They had assumed the streamlined fish-shape just as some of our modern sea mammals have. In fact, they very closely resemble living in the sea so long as to
long-snouted dolphins.
THE TERRIBLE LIZARDS Of
course,
when we speak
195
we
of ichthyosaurs,
don't speak of a
particular animal, but of a large group of diverse animals.
There
were species of ichthyosaurs that were no more than 2 feet long, instance,
and other
largest ichthyosaurs
and were, mals
species
which reached lengths of 60
were the
size
feet.
for
The
modern sperm whale
of the
in their time (180,000,000 years ago), the largest ani-
alive.
By
40,000,000 years
the giant species had died
later,
out and considerably smaller species, with shorter
tails
and no
teeth, took their place.
We arrive now at a tricky point. The ichthyosaurs, outward
fishlike
appearance, are complete and
despite their
thoroughgoing
They are quite extinct and some of them were enormous. Does not this qualify them— as large, extinct reptiles— to be considered among the dinosaurs? reptiles.
In popular speech, they surely are, but to purists this proper. Almost
all
long to a particular subclass of Reptilia, and Parapsida Strictly speaking, creatures outside that
on the term and
is
not
the creatures popularly called dinosaurs beis
not
it.
one subclass have no claim
in that sense the ichthyosaurs are not dinosaurs.
Passing on to Euryapsida,
we have
other aquatic creatures only slightly
as the
best-known examples
less well
adapted for sea
life
than the ichthyosaurs. All have limbs adapted for paddling and
swimming. Some look land, but clearly
one group
though they can
so completely paddle-equipped
cannot leave the
lizards,"
hobble around on
as is
sea.
still
These are the Plesiosauria
because they looked pretty
much
that
it
("near-
like reptiles except for
the oddity of four paddles in place of ordinary limbs). If
the ichthyosaurs were the reptilian equivalent of whales and
dolphins, the plesiosaurs seem to be reptilian seals. Their most re-
markable attribute, perhaps, were the long necks possessed by
most (but not
all) of
them. These were probably sent darting
ward, like animated spears, after
fish.
for-
At the height of the age
of reptiles, 100,000,000 years ago, certain varieties were 50 feet
long or more, with necks making up two-thirds of this total
THE SOLAR SYSTEM AND BACK
196
One
length.
of these gigantic varieties, the Elasmosaurus ("plated
lizard"), probably
The
had the longest neck ever
plesiosaurs look
dinosaur than
the
long necks and
tails,
much more
ichthyosaurs
and
They have
do.
And
a barrel-like body.
on Earth.
existing
like the ordinary
notion of the small
heads,
yet the plesio-
saurs are not dinosaurs because they, too, like the ichthyosaurs,
belong to the wrong subclass.
That brings
us to a fifth kind of reptilian skull. In a purely rep-
tilian sense, that fifth is
the most successful by
far. (I
qualify the
statement because the synapsids, although only moderately successful as reptiles, did give rise to the
be considered an enormous,
mammals, and that must
non-reptilian, success.)
if
In this last kind of skull, there are two openings behind the
eye socket; such a skull
There
a "diapsid"
is
son for that
that there are
is
no
of reptiles with diapsid skulls session of the
The
rea-
than two important groups
and neither can claim
sole pos-
title.
of the diapsid
Lepidosauria
("scaled ("scaly,"
from Latin), which reptiles,
less
skull.
The
from Greek). This includes the order, Squamata
first
lizards,"
("two openings")
however, no one subclass bearing that name.
is,
subclasses
in turn includes the
is
most
successful of living
the snakes and lizards.
Another order of lepidosaurs, Rhynchocephalia ("snout-heads," because they have prominent, beaky snouts),
is
completely different reason; not because
is
because
gin—a
it
it
interesting for a flourishing,
but
has avoided extinction by the narrowest possible mar-
single rare species.
The
order was never very important
and, except for that one survivor, died out about 70,000,000 years ago.
But there remains that one
lizard-like creature,
snout to
main
tail tip.
In recent times
it
was
still
is
a moderately large
long, at most, to
from
be found on the
New Zealand, but no longer. It is now to be found offshore New Zealand islets, where it is sternly pro-
islands of
only on a few
survivor. It
no more than 30 inches
THE TERRIBLE LIZARDS tected by law. Its tive
common name
197
tuatara ("back-spine," in na-
is
Maori, since in addition to the scales that cover
down
has a line of spines
backbone).
its
sphenodon ("wedge-tooth"), which Despite
looks,
its
it is
not a
that no lizard possesses (the
is
lizard. It first
Its
the
body,
it
more formal name
is
name
of
its
its
genus.
has a bony arch in
skull
its
giveaway to the early dissectors
that they had something unusual in hand). There teeth are at-
tached in non-lizard-like fashion and
membrane"
which birds
it
also has a "nictitating
possess,
but not
lizards. Fi-
has a particularly well-developed pineal gland at the top of
nally, it its
in its eyes,
brain,
something
lizards
In the young sphenodon,
do not have nearly
a third eye, though there
as well-developed.
bears the anatomical appearance of
it is
no indication
yet that
it
light-
is
sensitive.
The second and to
it is
diapsid subclass
this subclass,
and
is
Archosauria ("ruling reptiles"),
this subclass only, as the
name
implies,
which dinosaurs belong.
Of
we might
course,
out of creatures that
all
why two
have diapsid
skulls.
made
subclasses are
Well, there are other
For one thing, the archosaurs have teeth
distinctions.
sockets
stop to ask
and the lepidosaurs (with one very minor
set
in
exception) don't.
This seems an unimportant distinction to the layman, perhaps, but
it isn't.
The improvement
in tooth efficiency
is
such that the
archosaurs became, for a time, the most successful of tilian
subclasses. Besides,
sentative of a
The most
one such distinction
whole family of
it
is
usually repre-
distinctions.
primitive archosaurs
("socket teeth"), and
is
the rep-
all
make up the
from these that
order Thecodontia
all
other archosaurs
developed, though they themselves are long since extinct.
Many
of the thecodonts were rather
adopted a bipedal posture. The
on the small
side
forelimbs were reduced in
and size,
the hind limbs enlarged and strengthened, and a long balancing tail
was developed. They rather looked
like reptilian kangaroos.
THE SOLAR SYSTEM AND BACK
198
Certain heavier and clumsier thecodonts, however, were forced
on
to remain
which
dilia,
all fours,
and these developed into the order Croco-
The
survives, of course, to this day.
and
alligators
crocodiles are the only living reptiles that belong to the subclass
And
Archosauria, the one to which the dinosaurs belonged. crocodiles are not to
are their closest living relatives.
two
and only two
orders,
gators
and
yet
be considered dinosaurs, even though they
The
dinosaurs are restricted to
The
orders, within the subclass.
crocodiles are outside those
two orders and are
alli-
there-
fore not dinosaurs.
More spectacular which make up the
is
another group of thecodont descendants,
order Pterosauria ("winged lizards"). These
developed long thin webs based on enlarged
were lighter
still,
little fingers,
made wings out
of them,
and were the only
reptiles
ever to engage in true flight.
The long
early pterosaurs
tails,
too.
The
and often lacked teeth
much
ones grew larger, had altogether.
the skies held the largest of
and tails,
all
About 150,000,000
years ago,
the pterosaurs. This was Pterano-
feet and a long-crested skull some 3 feet from end to end. But the pterosaurs were not the only descendants of the the-
don.
had
teeth,
shorter
had long heads with sharp
later
It
a
wing span of about 20
codonts to learn the secret of true verted
its
scales into feathers.
From
flight.
creatures, the birds, so radically different
so
many
Another group con-
these descended a group of
from other
reptiles in
ways, as to deserve being placed in a class of
its
own,
"Aves."
There now remain the two orders of archosaurs (both extinct)
that contain the dinosaurs.
ship to other reptiles,
mainly with zoological
I
To
simplify their relation-
have prepared Figure
classification
and
entirely
is
8,
which deals
not primarily con-
cerned with lines of evolutionary development. If
the two orders could be grouped into one, that combined
order would undoubtedly have retained Owen's
title
of "Dino-
the terrible lizards
199
Figure 8 The Reptiles
ARCHOSAURIA
EURYAPSIDA
(diapsid skulls)
i
V PTEROSAURS
V DINOSAURS
TUATARA
V
TURTLES
SNAKES & LIZARDS
V MAMMALS
sauria."
However, a closer study of the creatures early showed that
there were important distinctions to be
made among them,
no-
tably in the pelvic girdle (or hipbone).
Since the ancestral dinosaurs had the bipedal gait of the thecodonts, the pelvic girdle had to bear the
The
pelvic girdle
full
was strengthened therefore and
bones enlarged in the course of evolution. of the girdle, the ilium, was enlarged
is
characteristic of
its
three chief
The uppermost bone
and came
backbone to produce a structure of great This fusion
weight of the animal.
to
be fused
solidity
both orders and
is
to the
and strength. therefore an
important characteristic mark of the dinosaur.
There are two other bones to the
girdle,
however. In some
dinosaurs these remained well separated and were set nearly at right angles. This rather resembles the situation in living lizards
and
so
all
dinosaurs with this arrangement of hipbones are placed
in the order Saurischia ("lizard-hip").
In the remaining dinosaurs, the two lower bones of the pelvic girdle are lined
up
closely parallel
and
slant backward. This ar-
THE SOLAR SYSTEM AND BACK
200
rangement resembles that
in birds
and
so these are placed in the
order Ornithischia ("bird-hip").
Nor
is
ticeable
anyone
the distinction a petty one in zoological terms. So no-
is it,
that once the difference in hip girdles
whether a dinosaur belongs
at all can tell
explained,
is
to
one group
or the other by one quick glance at the skeleton. It is for this
term.
logical
reason that "dinosaur"
One
can,
is
no longer
a formal zoo-
and often does, speak of "saurischian
dinosaurs" and "ornithischian dinosaurs." It
is
more
appropriate,
however, to speak of "saurischians" and "ornithischians," leaving out the word "dinosaur" altogether.
The
saurischians
had
their
two suborders, Theropoda
heyday
first.
("beast-feet")
These are divided into
and Sauropoda
("lizard-
bones of the former more closely resemble
feet"), because the toe
mammals in number than do the toe bones of the latter. An easier way of distinguishing the two suborders is to remember that the theropods are bipeds and the sauropods are those of
quadrupeds.
The
earliest of
the theropods were, in
thecodonts— light, small bipeds adapted were the Coelurosaurs ("hollow
lizards,"
fact, very
much
because
it
chicken and was the smallest of the
known
However, there was a general tendency
tition
on
among
strength.
wore
of
on—perhaps
size of a
dinosaurs. for species
to
grow
because increasing compe-
the various dinosaurs put an increasing
By
Many
and one, Compsognathus ("elegant jaw"
was so small and delicate), was only about the
larger as the ages
These
because their bones were
hollow for the sake of lightening the body structure). these were quite small,
like the
for fast running.
premium
the late Cretaceous, 80,000,000 years ago, coe-
lurosaurs the size of ostriches
almost exactly the
size
had evolved. One of them was ostrich, with a small head
and shape of an
sporting a horny, toothless beak, a long neck, and powerful legs.
Even though
it
had forearms with clutching
fingers instead of
THE TERRIBLE LIZARDS stubby, vestigial wings, and a long called
tail
201
instead of plumes,
it is still
"Ornithomimus" ("bird-imitator").
Another lizards"),
was
theropods
of
line
so
called
the
"carnosaurs"
So were the coelurosaurs, as a matter of
eating.
("meat-
because they were characteristically meat-
physical appearance of the carnosaurs
made
but the
fact,
much more
the fact
horribly evident in their case.
The
carnosaurs retained the bipedal structure but went in for
beyond anything the coelurosaurs could do. By the
size far
Cretaceous,
had reached
this
legs
to
tiny,
be of any
The
not
from
its
length of
full
late
Tyrannosaurus carried its
like 50 feet,
some
body, from
but
its fore-
longer than a man's, and far too short
couldn't even reach the mouth.
many
on
(which
is
teeth were
skeleton alone that
up it
clumped the Earth.
creature that ever
to six inches long
and
it
was the most nightmarish It is
the largest land car-
record, being at least as massive as the largest elephant
herbivorous) that ever lived.
The enormous it
in
jaws of the Tyrannosaurus could do their work without
clear
nivore
much
They
use.
help, however. Its is
The
was probably something
tail tip,
were
maximum
whose four-foot-long head was
("master-lizard"),
nineteen feet above the ground.
snout to
its
thighs of the Tyrannosaurus
was approaching the practical
The sauropods were
gigantic creatures,
in appearance, of all dinosaurs. structure, with long necks at
show
clearly that
limits for bipedality.
and the most
They were
familiar,
super-elephantine in
one end and long
tails at
the other.
Indeed, they looked like giant snakes that have swallowed giant elephants, with the columnar legs of the latter breaking through
and walking There are
off
with the creature.
clear signs of the bipedal ancestry of the sauropods,
for all that they
clumped down
cases, the forelegs
their backs sloped
The
longest
of
so hard
on four
legs.
remained shorter than the hind
upward and reached a peak all
the
sauropods
is
In most
legs so that
at the hips.
Diplodocus
("double
THE SOLAR SYSTEM AND BACK
202
beam"). Some specimens have been found which measured nearly 90 feet from the snout to the
tip of its
long tapering
No
tail.
other
animal was ever longer except for some of the very largest whales.
However, the diplodocus was a slenderly built creature and
was by no means the most massive dinosaur. The Brontosaurus ("thunder-lizard"), though shorter,
was more massive and may
have weighed up to 35 tons.
More massive
still
was the Brachiosaurus
called because, in the course of evolution,
("arm-lizards,"
so
forelimbs had finally
its
developed to the point where they had overtaken the hind limbs
and were longer). The Brachiosaurus may have weighed up
to 50
tons and was the largest land animal that ever lived. It is
how
hard, though, to be sure
"land animal."
It is
they could clump about on land,
and lakes
as
They found
we can
far
justify the
phrase
very likely that the large sauropods though if
modern hippopotami
necessary, lived chiefly in rivers
do,
and
for the
same
reason.
their food there, as well as a certain protection,
and
the water buoyed up their giant weights.
The
ornithischians,
groups, did not
come
which were the more specialized of the two into their
own
until
about 150,000,000 years
had already
ago, tens of millions of years after the saurischians
developed into a variety of flourishing forms.
The
ornithischians were
all
herbivores and their smaller repre-
sentatives also retained the bipedality of the original dinosaurian
ancestor,
case
though
among
their forelimbs never got as small as
Typical were the duck-billed dinosaurs, broad,
flat
jaw to handle their vegetable
Anatosaurus
was the
the saurischian bipeds.
("duck-lizard"), stood
diet.
which developed a
The
largest of these,
18 feet high.
It
might
re-
semble a Tyrannosaurus when seen quickly, from a distance, but it
was quite harmless unless
Most
it
stepped on you or
fell
on you.
of the ornithischians developed protection against the
THE TERRIBLE LIZARDS
203
One
carnosaurs by developing armor of one sort or another.
known
best
because
its
it
was
first
a roof. Closer study
assumed, protected
armed with two
for
its
tail,
showed
front legs were
more than
little
head contained a brain no
though
it
The
stegosaurus
It
became
is
feet long
tacks
bony
like shingles
double
in a
tail
was
spikes.
of ancestral
bipedality,
half the length of the hind.
larger
than a modern
kitten's,
and more massive than an elephant.
the very epitome of dinosaurian brainlessness. the early Cretaceous, probably before
extinct in
Tyrannosaurus appeared on the scene.
Walt
bony
signs
clear
Its tiny
was 30
back
while the tip of the
pairs of long, pointed
stegosaurus
its
showed that they stood on end
row from neck to the root of the
The
name
its
skeleton was found in association with large
plates which,
on
Stegosaurus ("roof-lizard"). It received
is
of the
The famous sequence
in
Disney's production Fantasia in which a Tyrannosaurus at-
and
kills
a Stegosaurus, though highly effective,
is
very likely
anachronistic.
An
armored ornithischian that evolved
later
than Stegosaurus
and was indeed contemporary with Tyrannosaurus was Ankylo-
and
saurus ("crooked lizard"), ily
armored creature of
all
this
was probably the most heav-
time. It was a low, broad dinosaur that
could not be easily overturned to expose Its
back, from skull to
which, along the
ended
in
sides,
tail,
its
unarmored
was layered with massive bony
were drawn out into strong
a bony knob that probably had the
spikes.
belly.
plates,
The
tail
force of a battering
ram when swung. It was a veritable living tank and I wonder what a battle between it and a Tyrannosaurus would have been like.
Finally there
is
the Triceratops ("three-horned"), which was
built like a super-rhinoceros
and
is
the best-known of a large and
varied family. Its armor was concentrated in
broad
frill
its
head region.
of bone, six feet across, extended from the head
covered the neck.
The
face bore three horns,
A
and
two long sharp
THE SOLAR SYSTEM AND BACK
204
ones over the eyes and a shorter, blunter one on the nose. In addition, the
mouth was equipped with
a strong, parrot-like beak.
For a summary of dinosaur relationships, see Figure
9.
Figure 9 The Dinosaurs REPTILIA
1 ARCHOSAURIA
IT
v
I
lRAPODS
sauropods
TYRANNOSAURUS
iguanodon
v stegosaurus
1
i
ankylosaurus
triceratops
diplodocus,
BRONTOSAURUS. BRACHIOSAURUS
But then came the end
of the Cretaceous, 70,000,000 years ago,
and something happened; we don't know what. All the dinosaurs that then existed, both saurischian and ornithischian, died off in a relatively short time, say a couple of million years. So did the
spectacular non-dinosaur
reptiles,
the ichthyosaurs,
plesiosaurs,
and pterosaurs. So did some spectacular creatures who were not reptiles,
such as the invertebrate ammonites.
There have been almost
as
many
theories to account for this as
there have been paleontologists, and lately there was published a particularly interesting
one which
I
will discuss in the next chapter.
THE DYING LIZARDS
15
Nearly twenty years ago
I
wrote a story called "Day of the Hunt-
ers" in which, in fictional form,
I
new
presented a
theory to ac-
count for the sudden death of the dinosaurs at the end of the Cretaceous period, 70,000,000 years ago.
The I
theory was a simple one.
Toward the end
of the Cretaceous,
suggested, a certain group of small dinosaurs
intelligence, invented missile
had developed
weapons, and hunted
all
the other
dinosaurs to extinction. Then, for lack of any other prey, they
hunted themselves to death,
Why
dinosaurs
with
large
few
fossils.
tures leave
and primates artifacts
But think
I is
.
.
too.
no records of
are there
are
brain
intelligent dinosaurs, then, or say,
capacities?
Well,
not here to defend
defensible.
call
crea-
.
am
I
used
it
my
thesis,
which, actually,
merely to write a
turned out to be what the science-fiction
would
intelligent
Look how few primate fossils we discover, much more recent than the dinosaurs. As for
little
critic,
I
don't
story (which
Damon
Knight,
"minor Asimov") that would develop a not-too-subtle
moral for our own times.
The problem
remains, though.
What
killed off the dinosaurs?
THE SOLAR SYSTEM AND BACK
206
For 150,000,000 species
years,
an astonishing
had dominated Earth's
life
is
them
forms. (I will call
saurs" in this essay even though, as
chapter, this
bulky reptilian
series of
I
"dino-
explained in the preceding
an inadequate term.) All through
this 150,000,000-
year period, from 220,000,000 years ago to 70,000,000 years ago, individual species of dinosaurs
out leaving descendants as
became
far as
sometimes with-
extinct,
we know, and sometimes having
previously branched off other species which, in a sense, replaced
them.
On
other occasions, a species might grow extinct in the
sense that
it
underwent slow changes that turned
species, or into several
About 70,000,000
new
years
however,
ago,
within a couple of million years perhaps) saurian species
A
hundred
became
fifty
extinct, leaving
quite
suddenly
the remaining dino-
all
was easy to explain, because at
years ago this
an age when the Bible was
truth, biologists
had
an Earth, and of
still
among
revered as literal
to square the gathering evidence in favor of
fossil creatures,
both many millions of years
with a Biblical tale that made creation of both Earth and to
(say,
no descendants behind.
that time the doctrine of "catastrophism" was popular biologists. In
new
into a
it
species.
life
old,
seem
have taken place merely 6000 years ago.
A
hint to the solution was found in the tale of the Flood.
Swiss naturalist, Charles Bonnet, suggested in 1770 that
A
fossils
were remnants of extinct species that had been destroyed in
any of a
series of
world-wide cataclysms of which the Biblical
Flood was only the most recent. After each such cataclysm
life
would begin anew, and
say-
ing that
it
Biblical truth could
dealt only with the
be preserved by
most recent of
several different
creations.
The most prominent exponent
of such catastrophism was the
French naturalist Georges Cuvier, who, in the great
skill
he compared the anatomy of the
that they could be arranged in a logical
decades of
first
the nineteenth century, was the foremost student of fossils
fossils.
With
and showed
manner and
fitted into
THE DYING LIZARDS still
existing phyla.
fairly
207
Using hindsight, we can see that what he did
shouted "Evolution!" at the top of
its
voice.
But Cuvier did not accept evolutionary explanations. he carefully pinpointed the location of four places
Instead,
in the fossil
record where there seemed gaps. These, he held, were four examples of Bonnet's catastrophes.
More and more
Alas for Cuvier! their order in all
the gaps disappeared. There
ment the
were discovered and
fossils
fossil
no point
is
in time
record begins (at a point
600,000,000 years ago) to the present, where to exist. Life
In
have existed with
The
dinosaurs.
very
much
little
A ago.
cease
life
still
alive
and
flourishing today that
horseshoe crab
is
an example:
it
has not changed
in 300,000,000 years. in the history of life
when
a great
species have indeed "suddenly" ceased to exist, while a great
other species kept right on going, and this
"partial catastrophe"
killed off
many
variety of habitats— the pterosaurs in the air in the sea, as well as the
other species intact.
mammals
lived right
The
And
plant
hard to explain.
species in a
years
wide
and the ichthyosaurs
clumping land dinosaurs, while leaving early ancestors of the birds
and of the
through the end of the Cretaceous. So did
the ancestors of the reptiles that cestral crocodiles,
is
must have taken place 70,000,000
Something happened that
saurs.
to be
forms of
all
change ever since before the time of the
Yet there have been times
many many
from the mo-
we now know
was created only once.
there are species
fact,
And
time was more and more clearly worked out.
still
live
which were not-too-distant life
lasted
today—even the
an-
relatives of the dino-
through the end-of-the-Cretaceous
dividing line practically untouched.
What a
the answer might be nobody knows, but there have been
number
of interesting speculations
on the matter.
For instance, there might have been a climatic change. The dinosaurs
may have been adapted
to a mild Earth of flat land
208
THE SOLAR SYSTEM AND BACK
and shallow
seas,
with
seasonal variations.
little
The
period of mountain building.
Then came
land heightened and grew
rugged; the sea deepened and grew cold; the seasons
extreme— and the dinosaurs died I
don't like this myself— at
a
became more
off.
least,
not as a sole explanation.
Surely the Earth didn't get climatically unsuitable everywhere.
managed
Creatures have
went bad. The
things
nia; the tuatara
hang on
to
to restricted habitats
when
giant redwoods cling to places in Califor-
clings
to
New
islands off
its
there
must have remained mild and marshy
some
of the smaller dinosaurs might have
Zealand. Surely,
areas
where
hung on,
at least
at least for a
while.
And
could climatic changes alone
relatively
Or furry
the ichthyosaurs in the
kill
unchanging environment of the sea?
perhaps
it
was the
living
environment that did
it.
The
little
proto-mammals, scurrying through the underbrush and do-
ing their best to evade the eyes of the lordly reptilian masters,
might nevertheless have grown for themselves
And
fat
on dinosaurian eggs
left to care
by the dim-witted saurian parents.
eventually the
mammals might have
eaten enough eggs to
block the generations and awoke one morning to find the reptiles gone.
It is
to the
way and
a dramatic story in a
ground since
egg-eaters can
There are
it
presents us
suits us right
down
as heroes (if skulking
be considered heroes).
difficulties,
in existence for a
of course. Primitive
mammals had been
hundred million years by the time the Cretaceous
period drew near
its
increased in numbers
dinosaur eggs.
mammals
it
Or
end.
We
must suppose that they suddenly
and began
else
we can
to take
an unbearable
decide that certain
new
toll
of
species
developed that specialized in these eggs, while leaving reasonably
untouched the eggs of the ancestral
snakes,
And,
and
crocodiles,
lizards,
turtles.
for that matter,
how
did these
mammals
get at the eggs
THE DYING LIZARDS
200.
of the ichthyosaurs, which brought forth their in the sea, in
Then
any
young alive— and
case.
make we sup-
there are the falling-domino modifications that
capital of the fact that life
is
Why should
interdependent.
pose something had happened that affected every single one of the extinct species alike? Perhaps only a relatively small
number
and when these began to dwindle and
of species were affected,
die out, other species which
depended upon the
first
set
for
food or for other necessities also died, and these in turn brought
about the extinction of others—until a whole swatch of the fabric
of
life
was cut out of
This must happen
now.
If
existence.
the time. It can easily be seen as a threat
all
the eucalyptus tree were to
would have to become
become
extinct, too, for
it
extinct, the koala
nothing but
will eat
eucalyptus leaves. If the zebra population were to vanish overnight, the African lions It
would
drastically decrease in
doesn't even have to be a matter of food.
numerous
species
pollination will
Something Cretaceous.
A
plants
of
be wiped out
like that
that
Wipe
numbers.
out bees and
depend on bees
for
cross-
also.
may have happened
at the
end of the
group of species that formed part of a particularly
tight interweaving of life died out,
and with them the
rest of
the
web went. But what could the
initiating factor
have been?
Could a climatic change have killed some species and set the falling? Did a group of egg-eating mammals kill off some species? Was it perhaps the advent of some new strain of
dominoes to
bacteria or virus that killed off certain species in a vast plague?
Was
it,
on the other hand
(as I
have seen suggested), a plant
Did the development of some precursor of modern grasses, which are hard, tough, and ruinous even to the highly adapted molars of the modern horse, bring about the end? The herbivorous dinosaurs, used to softer, more succulent vegetation evolution?
(and possessing teeth to
suit)
began, perhaps, to decline as the
THE SOLAR SYSTEM AND BACK
210
grasslike plants spread species.
And
more and more
at the expense of the earlier
with the herbivores dying, the carnivores that fed
upon them had
to starve as well.
remains only to choose the particular mechanism that set
It
the dominoes to falling, and so far no one has been able are too
many
possibilities to
There
to.
choose from and no reasonable
evi-
dence upon which to base the choice. Indeed, I've
I
haven't even discussed
the possibilities yet. So
all
mentioned only causes that could be one-shots
totally unpredictable. After all,
radical
weather change?
will there
late
sions
will there
will a
be another
really
When
new plague come?
be the equivalent of creatures to eat our eggs or plants
to set our catties' teeth It is
When
when
far,
or, if periodic,
much more
on the
on edge?
interesting, in a grisly sort of way, to specu-
possibility of
reasonably predictable periodic occa-
on which there would be a Great Dying.
We
do, in fact,
find signs in the fossil record of periodic events of this kind, with
the one at the end of the Cretaceous the most spectacular only
because
it
is
one of the most recent and therefore has
record best preserved. There was a of the huge ulating
mammals
still
more
fossil
its
recent Great
Dying
only a couple of million years ago. (By spec-
on such periodic Great Dyings, be it noted, we turn the wheel full cycle and are back to something a little bit
scientific
like Cuvier's catastrophism.
This often happens in science.)
what might possibly give rise to a pemore or less fixed intervals, would place upon life forms and weed them out with a kind
Let's think, then, as to riodic effect which, at
enormous
strain
of blind ruthlessness. It
has sometimes been suggested that there
expectancy to species; that species,
is
a natural
like individuals,
life-
have a lusty
youth, a vigorous prime, a fading old age, and then a senile death.
Perhaps the Great Dyings take place when the species-lifetimes of a large gether.
number
of species just
happen
to reach the
end
to-
THE DYING LIZARDS Actually, there's
no evidence
211
at all that species
the sense that individuals do, but can
we put
grow
senile in
things in other terms?
Instead of talking of senility and life-expectancy,
let's talk
of
mu-
tations.
All species are constantly subject to mutations,
and mutated
individuals arise in each generation. In the vast majority of cases,
and the mutated forms survive
these mutations are for the worse
than do the normal.
less well
and
ever,
if
If there are
species as a whole, the species can it
succumbs to
be weakened to the point where
enemies. In that sense, the species
its
viewed as growing
Then,
too, particular species
creatures have
may
develop a tendency for
grown so
is
more
creature with too elaborate a set of
structure
may
likely to
cer-
happen
specialized that they are oversen-
changes in the environment or in their
sitive to
A
may be
"senile."
tain types of disastrous mutations. This
when
enough mutations, how-
the mutated forms are enough of a burden on the
own
physiology.
armor or too unbalanced a
pass beyond the practical with even a small change.
We ourselves are not immune. We have an extraordinarily complicated
mechanism—in many stages—of blood
clotting.
Our blood mean that
clots
with remarkable efficiency, but the complications
it is
subject to an unusually high failure rate since there are so
many
stages that can
go wrong.
cur in each generation of tion in the clotting live
A sizable number of mutations
oc-
mankind that involve some imperfec-
mechanism. The resultant "bleeders" cannot
long without heroic measures.
Again, the
human
species has developed
an enormous head to
house our giant brains. The female pelvis has barely kept pace
and infants are born with outsize
skulls that
can barely squeeze
through the pelvic opening and even then only at the price of distorting the still-soft cranium. In several ways, then,
piens in
is
at the ragged
mutation
Homo
edge of disaster and cannot afford a
sarise
rate.
Suppose now there
is
an increase
in the
mutation
rate.
If
a
THE SOLAR SYSTEM AND BACK
212
species or group of species
few
tively
likely
is
so well balanced that there are rela-
mutations that can result in death,
that increase moderately well.
it
can endure
on the other hand, a species
If,
is
near disaster in some way, a sudden increase in the mutation rate
might
wipe
just
it
out.
the causes bringing about an increase in mutation rate are
If
temporary, then only certain vulnerable species will go, while the less
may
vulnerable ones
survive, albeit
somewhat ravaged and
changed.
Perhaps
all
the dinosaurs shared something that
made them
particularly vulnerable to the ravages of certain mutations. Per-
haps
went
all
(either directly or as part of the chain of life)
when mutation
rates
climbed at the end of the Cretaceous. Those
that survived (including our vulnerable, that's
And
own
ancestors)
happened
to
be
less
all.
perhaps there are additional periods of increased muta-
tion-rates to
come, and perhaps
we won't
sical chairs,
But what
is it
game
in the
among
always be
What would
that happens?
mu-
of evolutionary
the winners.
raise
the mutation
rate?
One answer
bombarded by hard
why
know,
is
itself,
radiation.
The Earth
There
is
the
one thing. However, there
is
is
ra-
no
that radioactivity should suddenly increase at particuit
can undergo, as
far as
we
that of a slow but steady decrease.
What about the radiation —the
for
In fact, the only change
lar times.
is
radiation of varying origin.
dioactivity of the crust
reason
mind
that springs to
Sun's radiation,
bombards Earth from outer space and the cosmic rays from beyond the solar that
system?
Much it
of this radiation
is
absorbed by the atmosphere before
reaches the Earth's surface and
trically
charged components of
netic field.
As a
much
it) is
of
it
(at least the elec-
deflected by the Earth's
result of this deflection, the
Earth
is
mag-
surrounded
THE DYING LIZARDS by regions
in
which charged
21$
high density, dance back
particles, in
and forth along the magnetic lines of force (the
and leak down to
Van
Allen belts)
into the upper atmosphere in the polar regions
form the auroras. Clearly,
if
Earth's magnetic field were to vanish, charged par-
would no longer be
(including the cosmic-ray particles)
ticles
deflected
and more of them would
would be
effect
mutation
strike
the Earth's surface.
The
to raise the radiation level and, therefore, the
rate.
But could the Earth's magnetic Possibly!
vanish?
field
Consider the Sun, for instance.
sunspot cycle, as
we
all
know. That
the
is,
It
has an 11-year
number
of sunspots
rises steadily, reaching a maximum, then falls to a minimum that is nearly zero, then rises to another maximum, and so on. The
length of time from
maximum
maximum
to
averages 11 years,
though the actual time lapse between recorded maxima has varied
from 7 to 17
The
years.
sunspots have magnetic fields associated with
the orientation of the magnetic ispheres. If in the
them and
opposite in the two hem-
field is
Northern Hemisphere, spots have the north
magnetic pole on top (so to speak), those in the Southern Hemisphere have the south magnetic pole on top. Then, in the next cycle,
the situation switches.
The Northern Hemisphere
spots
have the south magnetic pole on top and the Southern Hemisphere spots have the north magnetic pole there. cycle magnetically as well as numerically It is
not certain whether
this
To
restore the sunspot
one must wait 22
years.
means that the Sun's general mag-
netic field regularly reverses polarity so that every 22 years the
Sun's north magnetic pole becomes
its
south magnetic pole and
vice versa. If this happens,
one must not suppose that the mag-
netic axis suddenly topples
and turns
pens
is
that the entire magnetic field
and then begins to strengthen again
over.
What
probably hap-
weakens and declines
to zero
in the opposite direction, with
THE SOLAR SYSTEM AND BACK
214
sunspot minima probably coming at times of zero
happens (assuming
Can field?
it
field.
Why
this
does happen) no one knows.
much
the same thing happen to Earth's
Well, there are indications in the rocks
when
the north magnetic pole
now
(as, for instance, in
that there have been
the orientation of magnetized minerals) periods in Earth's history
smaller magnetic
the south magnetic pole was where is
and
vice versa. Presumably, this
happens because the Earth's magnetic
gradually fades to
field
zero, then strengthens in the opposite direction.
As
a matter of fact,
seems that the Earth's magnetic
it
indeed been weakening during the centuries
The American
observation.
Robert Gunst point out
it
has
McDonald and its
strength since
by
will reach zero
it
Between 3500 and 4500, the magnetic
a.d.
field
has been under
Keith
geophysicists
has lost 15 per cent of
1670 and at the present rate of decrease
4000
it
field will
not be
strong enough to ward off any charged radiation to speak of.
We
ourselves won't live to see
two thousand let
of course, but a matter of
it,
human
years isn't long even in terms of
alone in terms of geologic eras, and
it is
civilization,
not something
we can
dismiss with a shrug.
And
it is
a shame, for
close to a reversal.
may have
the rocks,
What 3500,
we
The
will
will
artificially,
it
seems rather bad luck for us to be so
last reversal, as nearly as
taken place as
much
happen when the magnetic
we can
tell
from
as 700,000 years ago. field fades?
Perhaps, by
have the technological capacity to shield the Earth
but suppose we don't. Will the mutation rate go up in
the thousand years of non-shielding and "senile" species?
Will we be among the
kill
the
senile? Is
less
stable or
Judgment Day
coming? Perhaps not. After field
may have
all,
reversed
when
the magnetic
there was no Great
Dying among
700,000 years ago,
itself,
man's hominid ancestors. They
mutation rate had gone up. At
may even have improved least
if
the
man's brain grew in volume
with explosive speed (in terms of ordinary evolutionary rates of
THE DYING LIZARDS change) and one might speculate that
215
was the
it
result of
an
unusual number of lucky mutations. Besides,
have seen calculations which showed that even
I
there were no magnetic field at
all
the surface of the Earth would
particles, the level of radiation at
not
increase the mutation rate dangerously.
rise sufficiently to
Suppose we tackle
if
and no interception of charged
it
from the other end. Forget Earth's mag-
netic field for a while,
and ask whether the radiation bombard-
ment might
increase drastically at the source.
X
its
rays
from
companies a giant tity of this
The Sun
sends out
corona as a matter of course and occasionally ac-
with a burst of soft cosmic
flare
radiation
too small to
is
harm
rays.
life,
The quan-
but what
if
it
suddenly increased in intensity considerably. It's
not
likely.
The Sun could
becoming much more
necessary to
ray emitter without of ultraviolet
and
scarcely
undergo the changes
active as
an X-ray and cosmic-
becoming much more
visible light as well,
active in the emission
and the Sun doesn't do such
things.
From
we know) about the Sun and about stars generally, and from everything we can deduce from the fossil record, an erratic Sun is not in the cards. Our good everything
we know
old solar heating plant ticeably
What we
utterly reliable
is
and hasn't changed no-
from eon to eon. about cosmic rays from sources other than the Sun?
These are the only that
(or think
significant nonsolar samples of
hard radiation
get.
Lately, K.
D. Terry of the University of Kansas and
Tucker of Rice University have speculated on the possible
W.
H.
effects
of stars going supernova in the neighborhood of our solar system.
They point out
that a good massive type II supernova (involv-
ing the virtually total explosion of a star ten times the mass of our
Sun) would give
off
up
to 2
of cosmic rays alone, emitting at most.
X
10 51 ergs of energy in the form
it all
over the period of a few days
THE SOLAR SYSTEM AND BACK
2l6
Let us say that of a week. It
this cosmic-ray
energy
would then be equivalent
the total energy delivered by the
How much were 16
Sun
times
1 trillion
in that week.
cosmic ray energies reaching us from
still
be equal to the Sun's
tion for that week. Undoubtedly, that
However, there are very few
enough to give
rise to
would
stars of
are as close to us as 16 light-years,
make
total radia-
fry us all properly.
any kind
now,
that, right
and of those that are none are
The
the biggest kind of supernova.
only close star that could go supernova at that would
delivered in the space
of that energy would reach us? If such a supernova
light-years away, the
that vast distance would
large
is
to roughly
all
would be
Sirius
and
a rather mild one.
However, we don't have to
insist
on a
total frying.
Consider
supernova explosions that take place at great distances and bathe us with smaller concentrations of cosmic rays. Those smaller concentrations might
room
ume
for
many more
of space goes
be enough to cause trouble and there
still
supernovas far away than close by.
up
as the
number within
vol-
cube of the distance and the number
of supernovas within 200 light-years as the
The
is
is
two thousand times
as
many
16 light-years.
Terry and Tucker point out that the present dose of cosmic rays reaching the top of the
per year, which
is
very
atmosphere
little,
really.
is
And
equal to 0.03 roentgen yet,
judging from the
frequency of supernova, their random positions and
sizes,
they
cal-
culate that Earth could receive a concentrated dose of 200 roentgens, thanks to supernova explosions, every 10,000,000 years or so,
on the
average,
and considerably
larger doses at correspondingly
longer intervals. In the 600,000,000 years since the
began there gen
is
flash (!)
fossil
record
a reasonable chance that at least one 25,000 roent-
reached
us.
Perhaps then the periodic Great Dyings in the history of reveal the explosions of large stars within a
few hundred
life
light-
years of our solar system.
And
perhaps the effect
is
worst
when such
a sizable explosion
THE DYING LIZARDS just
217
happens to come when the Earth's magnetic
field is in
period of reversal and the unshielded surface gets the of the cosmic-ray frying pan. After
now, much weaker than at times
make
its
our magnetic
all,
maximum. There
its
benefit
full
weak
field is
are probably
when even moderately strong doses of cosmic rays might not it, but now they will, and by 3 500 they will do so even more
A
readily.
supernova that in 300,000
would not have
b.c.
affected
Earth, might lay us pretty low now.
Well, then,
if
we
can find a record in the rocks that about
70,000,000 years ago there was a magnetic field reversal, and
if
we
can find a record in the skies that 70,000,000 years ago there was a
and
spectacular supernova in our neighborhood,
some way strongly
if
of showing they were simultaneous, then
tempted to look no further
there were I
would be
for the cause of the
death of
the dinosaurs.
And what about
our not-too-distant descendants? Must
our breaths and cross our fingers for them?
What
if
we hold
during the
thousand-year interval of virtually no shielding whatever, Sirius goes supernova, or a larger, but
The chances
more
are extremely small.
within several hundred light-years tionary development to then,
we
don't
know
all
make there
is
distant, star does it?
As
far as
we know, no
star
sufficiently late in its evolu-
a supernova explosion likely—but, is
to
know about what makes
a su-
pernova explode, and when. It just
barely could be.
enough to make
a Dying,
ensure the immunity of
And
if
we
be a kind of
die
The
cosmic-ray incidence
Great or
Homo
Little,
sapiens
and the crocodiles and
reptilian last laugh at
if
and there that
is
comes
may
go up
nothing to to pass.
lizards survive, there
our expense.
may
COUNTING CHROMOSOMES
l6
am
Alas, I
a square.
secret urgings
nical
I
don't use mind-expanding drugs,
toward psychedelism,
term for marijuana); in
smoke tobacco.
I
wear
my
I
fact,
hair
I
I
have no
smoke pot (the
don't
tech-
don't even use alcohol or
and sideburns moderately
short,
have neither beard nor mustache, dress cleanly and conservatively (if,
on
occasion, sloppily),
and speak
a reasonably precise
English. I
do
all this as
a matter of personal choice, however,
out deep, moral convictions.
I
have no objections whatever to the
eccentricities of others, provided they leave
vided those eccentricities do no I
and with-
harm
to
me
to mine,
anyone but
and pro-
their owners.
consequently spring to the defense of the long-hairs against
my fellow
squares. In
ing out that those
makes them look
time,
I
have published
object to long hair
like girls"
shaving, for the very stance.)
my
who
same
pointit
ought to object to the practice of
reason. (See the next chapter, for in-
Yet they don't; but usually object
makes nonsense of the
little essays
on boys "because
logic with
to beards, too,
which they
which
try to invest their
prejudices.
In fact,
it
seems to
me
that the whole business of telling the
COUNTING CHROMOSOMES sexes apart at a glance
is
overrated.
Why
219
does one have
to quote
one
to, if
doesn't have a personal interest in a particular individual?
like
I
Roland Young's "The Flea":
And
here's the
happy bounding flea—
You cannot tell the he from she. The sexes look alike, you see; But she can So
and
was with some chagrin that
it
from a fall
tell f
girl
so can he.
I
discovered that telling a boy
can be important indeed and not at
of 1967, a Polish
woman
Her unclothed body was
clearly female,
placed that femininity in question.
all
simple. In the
was inspected by doctors.
athlete
but more subtle
The chromosome
tests
count,
it
seems, was wrong.
And what
are these
chromosomes that can thus contradict the
evidence of one's eyes in so vital a matter and get away with
Aha,
as
you have
just guessed,
The chromosomes body's
cells, visible
five to ten
I'm about to
tell
it?
you at length.
are tiny, flexible, rodlike objects within the
only under the microscope.
It
would take some
thousand of them, strung end to end, to stretch across
a single inch.
Even with cell.
Like the
through them cells
a microscope, they are hard to see in
the
easily.
For a century and a
cell,
half, microscopists studied
without seeing the chromosomes.
But then, a century ago,
some
the living
they are translucent and light passes
rest of
of the
new dyes
began treating
biologists
with
cells
that chemists were then starting to syn-
thesize. Different parts of a cell contain different chemicals;
parts therefore absorb a particular dye
and some do
under such treatment, begins to display
its
not.
some
The
cell,
inner structure in tech-
nicolor splendor.
In 1880, a
German
biologist,
Walther Flemming, was using a
THE SOLAR SYSTEM AND BACK
220
red dye, which clung only to certain patches inside the cell nucleus.
(The
cell
nucleus
in the cell. It
one
a small body,
is
more or
located
less centrally
was early found to control the manner
which
in
two cells— the key process of growth and
cell divides into
development.) Flemming called these colored patches of nuclear material "chromatin," from a Greek
Flemming was
word meaning
thing to do with the nuclear control of tunately, chromatin could only
the dye killed the
What
he
tissue, in
cells
were in
and then running
material collected
cell
into
itself
stills,
putting
moving picture
off a
turned out that as a
what looked
name of "chromosomes" ("colored moment of division, the chromosomes other.
The
"daughter
mass of
At the
separate into cell
and the
were produced, each containing
cells"
new
like a tangled
crucial
two equal rest to
then divided through the middle, and two
cell
Once
of chromosomes. in each
film.)
bodies").
one end of the
to
like taking
in the right
These pieces were soon given
the
one half going
was
them
got ready to divide, the chromatin
short pieces of cooked spaghetti.
parts,
cell
He
at every stage of
details of the process. (It
a set of scrambled photographic
It
stages of division.
putting the different stages in the right order,
he could work out the order,
growing
slices of rapidly all
and caught the chromatin
slice
By
be seen when colored by dye, and
was to study thin
did, then,
that process.
Unfor-
division.
cell
cells.
which individual
dyed the entire
"color."
eager to learn whether the chromatin had some-
division
its
own
the
new
supply
was complete, the chromosomes
broke up into patches of chromatin again.
Further study showed that a particular species of creature contained the same
number
of
chromosomes
one important exceptional case which not always easy to
tell
tangle together, and say
where one
what
when
leaves off
this
I'll
number
there are
in each of its cells (with
get to in a while)
is,
many
since the
of them,
.
It is
chromosomes it is
hard to
and another begins. The best attempts
COUNTING CHROMOSOMES at counting
chromosomes
in
human
cells
chromosomes per
that there were 48
more painstaking count showed only
Chromosome counting
seemed
to show, at
first,
In 1956, however, a
cell.
46.
now become
has
221
rather simple. Cells
are treated with a chemical that forces the process of cell division to stop short at just the point clearly shaped.
with a weak to swell,
These
salt solution
become
with very
cells,
little
puffy,
trouble,
where the chromosomes are most
caught in mid-division, are then treated
that causes the individual
and move and
in
They can then be counted
apart.
human
chromosomes
46 chromosomes turns
cells,
out to be correct.
But
this raises a question.
chromosomes?
when
a cell divides, shouldn't each
mosomes? And chromosomes be No! the
How
still
human
cells
have 46
new
cell
have merely 23 chro-
moment,
number
that momentarily doubled supply
of
there are 92
new
dividing cell and, after division, each
cell
number
of
fewer?
doubles. For a
pens at each
all
at the next division, shouldn't the
Just before cell division, the
cell
can
the chromosomes divide into two equal parts
If
and
division so that
is
chromosomes within chromosomes
cell
in the
has exactly half of
back to 46 again. This hap-
(again with one exception)
chromosome number remains 46 no matter how many times cells divide and share out their chromosome content.
the
The involvement
chromosomes in cell division is, as a matter of fact, very precise. The chromosomes aren't put together higgledy-piggledy at all. Chromatin comes together to form chromosomes of specific size and shape, and they are always formed of
The human
contain 23 pairs of chromosomes; these have been carefully numbered in order of decreasing length, from in pairs.
1
cells
to 22, with the twenty-third pair being a special case.
At the midpoint of the process of cell division, each chromosomes brings about the formation of another pair like itself. Since it
forms a replica of
itself,
the process
pair of
is
exactly called
THE SOLAR SYSTEM AND BACK
222
"replication." After replication,
and when the
are present; in such a
way
that
two complete
cell divides,
a particular pair
if
Each new
sets of
moves
one direction
in
its
ends with a complete
replica
moves
set of
chromosomes, one pair of each of the
in the other.
chromosomes
the chromosomes separate
cell
no
23, with
pair
missing and no pair added.
This careful division is
made up
necessary.
is
Each chromosome, you
of strings of genes, thousands of
mosome. Each gene
them
see,
in each chro-
controls the formation of a particular
enzyme
molecule, which in turn controls a particular chemical reaction going
on
in the cell.
The chromosomes, the
They
cell.
carry
does or can do
is
then,
it is
exact set of
instructions, so to speak. Everything the cell
made
enzyme supply and rally,
therefore, are the "chemical supervisors" of
its
possible
by the particular nature of
this is dictated
by
its
important that every new
chromosome
pairs so that
tions for the performance of
cell in
may
it
the body get an
possess the instruc-
its tasks.
(These instructions are basically the same for they are
somehow modified
so that liver cells are
part, brain cells in another, skin cells in
still
each with widely different functions and in
its
chromosomes. Natu-
all
cells,
produced
in
on-
another and so
abilities.
which the chromosome instructions are modified
but
one
The manner is still
a bio-
chemical mystery, however.)
The cision,
process of replication passes
from
cell to cell
on from parents appropriate
from set of is
to offspring?
chromosome
How
is
a
how
pre-
are they passed
new body
started with
instructions?
done by way of the sex cells. The female produces egg the male produces sperm cells. Each of these is distinguished
This cells;
chromosomes on, with
within a body. But
is
all
other
cells
by the
fact that they contain only half a
chromosomes; only one chromosome of each
the aforementioned exception to the rule that
contain the same
number
of chromosomes.)
all
pair.
human
At some
(This cells
stage in
COUNTING CHROMOSOMES the formation of the sex
cells a
without prior replication.
The
chromosome
egg
cell is
rest to
cell.
the other. tiny,
That, however, need not be wounding
to the male's ever-sensitive ego.
The
egg
cell is large
contains a sizable food supply in addition to contains chromosomes only.
cell
one of
tremendously larger than the insignificantly
tadpole-shaped sperm
sperm
division takes place
23 pairs simply separate,
each pair going to one side and the
The
223
its
because
it
chromosomes. The
From
the instructional
standpoint, the two varieties of sex cells are equal.
The
sex cells
produced by a particular individual are not
may be
all
alike.
Every chromosome pair
pair,
but the two individual chromosomes of the pair are not
exactly alike. (In other words
not
"Aa" may be
The two chromosomes
like "a.")
far as size
like every other
chromosome
"Aa," but "A"
like
may be
of a pair
is
twins as
and shape are concerned, but the molecular structure
may be significantly different. One particular sex cell may get chromosome "A" of the first pair or it may get chromosome "a." It may get chromosome "B" of the second pair or chromosome "b" and so on. The number of different combinations that may be formed by taking, at random, of the genes they contain
one of each of 23 twenty-three is
2*s
different pairs can
and multiplying them
be found by starting with together, 2 23 .
The answer
8,388,608.
Even
chromosomes can sometimes wrap themselves about each other and swap pieces in any of a thousand different ways. A sex cell may get a chromosome that
is
this
is
conservative, for pairs of
mostly "A" but slightly "a."
Then,
too,
it is
possible that a particular gene within a chro-
mosome may undergo
a change even while
it
is
part of a living
cell.
There are so many chances of variation tern received sex cell
of
by each sex
cell
that
it is
in the
instructions.
pat-
quite possible that each
produced by a single individual has a
chromosome
chromosome
slightly different set
THE SOLAR SYSTEM AND BACK
224
A
new
individual
is
formed only when a sperm
male parent combines with an egg produce a cells,
—23
"fertilized
the fertilized pairs,
ovum now its
possibilities of
from the
cell
of the female parent to
such a union of sex
result of
has a complete set of chromosomes
with one of each pair from
of each pair from
The
ovum." As a
cell
its
mother and the other
father.
combination of sperm
cell
and egg
cell pro-
duces a random reshuffling and recombination of genes from
two separate individuals to produce a new creature with a brand new set of chromosome instructions, not like that of either parent. With all the possibilities for variation among the sex cells produced by each parent,
mated 60
seems quite certain that each one of the
it
billion
humans who have
distinctly different
lived since time
from every other one, and that
tinue for the indefinite future. (Identical twins,
some
reason, divided into
this will con-
triplets, etc., are
exceptions for they arise from a single fertilized for
esti-
began was
ovum
two or more separate
that has, cells
that
then develop independently.)
This ceaseless variation in instructions from generation to generation through sorting
and recombination of chromosomes
is,
in fact, the probable biological basis for the value of sex. Creatures
can, after
all,
reproduce without
offspring without help; ever,
some
two parents combine
to
sex,
with one parent producing
types of species do this.
of chromosomes that takes place introduces scale
not possible otherwise.
species
to
is
greatly increased
When, how-
form a new individual, the
The
and
it
variations
and
versatility of a
flexibility
can evolve
much more
meet changing conditions. Sex has therefore
glad to say) replaced nonsex altogether
shuffling
new
among
all
(I
am
on a
quickly
personally
but the simplest
creatures.
The moment is
of fertilization—of the union of sperm with
significant with respect to the twenty-third pair of
It is
egg-
chromosomes.
the only one that need not be a true pair in outward ap-
COUNTING CHROMOSOMES pearance. In the female of
two
fairly
225
however, the pair being composed
it is,
long chromosomes, called "X-chromosomes."
male, having two of these, can be designated as an In the male, the twenty-third pair
them
normal X-chromosome, but the other
a
is
not a true
is
only about a quarter the length of the X.
chromosome" and the male
therefore
is
sex difference, the twenty-third pair of called the "sex
is
A
pair.
One
XY
and an in a
of
a stunted one,
The short one is a an XY. Because of
"Ythe
chromosomes are often
chromosomes."
Apparently, the differences in the enzymes produced by an set a
one ending
fe-
XX.
body on one or the other of two
in a female
XX
different paths,
anatomy and physiology and the other
male version.
The Y-chromosome means
in the male is largely nonfunctional, which X-chromosome has no spare as backup and a bit more vulnerable to certain genetic ab-
that the male
males are therefore
A
normalities.
defective gene in an
shows up; in a female
it
may be
X-chromosome
in
a
male
countered by a whole gene in the
other X-chromosome.
Some
"sex-linked characteristics," such as color-blindness
and
hemophilia, which appear in males but rarely in females, are very noticeable. Others are not but
female
may account
for the fact that the
span proves to be up to seven years longer than that
life
of the male once the dangers of childbirth are banished by
mod-
ern medicine.
When egg
a female forms egg
cell gets
content
is
When sperm
concerned,
a
cells
two broad
one X. As
all
egg
male forms sperm
end up with an varieties of
the
cells,
far as the overall
pair divides
and each
shape of the chromosome
cells are therefore alike. cells,
X and
sperm
XX
cells
the
XY
pair divides. Half the
half with a Y.
There
are, thus,
formed.
In the activity that precedes fertilization, several hundred million
sperm
cell.
The sperm
cells are released in
cells
the neighborhood of a single egg
(about half of them
X
and
half
Y)
race
THE SOLAR SYSTEM AND BACK
226 for the egg
cell,
reach the egg
XX
with winner take
first
and
fertilizes
and develops into a female. an XY; that
the result
is
and so
happens that boys and
it
is,
all. If
it,
an X-sperm happens to
then the
a male.
fertilized
ovum
an
is
Y-sperm makes the grade,
If a
The
chances are about equal
are born in roughly equal
girls
numbers.
we are assuming that all will go well, and not be so. The process of cell division, involving the So
far
cation of the immensely complex division
between two new
cells,
chromosomes plus can
easily
yet this
may
careful replitheir precise
go wrong and some-
times does. Errors can take place. Sometimes these will only involve individual genes
somewhere along the
chromo-
line of the various
somes. Such "mutations" can be fatal or merely disadvantageous.
There are even occasions when a mutation can be
favorable. affected,
but
an entire chromosome that goes wrong? In the process of
cell
But what division,
not a submicroscopic gene that
if it is
is
with the chromosomes being yanked roughly apart,
may happen
that one of
them may break
in
two and come back
together again with one piece rear-side forward.
chromosome-piece has speak,
and
is
its
it
A
backward
instructions reading differently, so to
not normal.
Or what if a chromosome breaks in two and does not reunite? The pieces might travel to opposite ends of the cell. One daughter cell may get a chromosome pair plus an extra piece of a third chromosome, while the other daughter
cell gets
not quite
all
of a
pair.
Such chromosome aberrations are much more changes in individual genes.
hundreds of genes
all
ring of instructions
is
at once.
serious than are
Chromosome breakage can
involve
Such a wholesale blurring and
almost certain to produce
cells
slur-
that cannot
and go through the intricate process of growth and division. If such chromosome breakage takes place in the cells of a hu-
live
COUNTING CHROMOSOMES man
adult,
cells,
do not count
One cell, or even a hundred much among trillions. The damaged cells
need not be
it
for
227
serious.
drop out and are replaced by those produced through correct vision. In
the
fact, since
true-formed
show up,
cells
accurate than
And what
it
damaged
may
to
be
more
far
really be.
the error takes place in the production of sex
if
and one appears with such such a sex
division seems
cell
cell
di-
drop out and only the
cells
a
chromosome
cannot develop
far.
cells
aberration? In general,
Those children who do man-
age to be born usually lack serious chromosome aberrations and
we get the idea that the processes of egg and sperm formation are much more foolproof than they really are. Heaven knows how many botched jobs are scrapped and never come to view.
A
hint of the botching arises from the fact that a few aberra-
tions
manage
some
five
to
make
it
and babyhood. One birth out of
to birth
hundred, for instance,
is
drome," or "Mongolism." (The
which seem to East Asians.)
The
of an infant with
latter
name
refers
"Down's
syn-
to the eyes,
slant in such babies in a fashion associated with
The
condition involves serious mental retardation.
cause of the syndrome was not
three Frenchmen,
Lejeune,
J.
the chromosomes in
cells
M.
known
until 1959,
when
Gautier, and P. Turpin, counted
from three cases and found that each
one had 47 chromosomes instead of 46. It turned out that the was in the possession of three chromosome-2i's, a normal
error
pair plus to a
an additional
chromosome
single.
formed
The sex 21, as cell
it
cell
first
disease ever pinned
aberration.
Apparently, what happens cell is
This was the
after
is
that every once in a while, a sex
an imperfect division of chromosome-pair
21.
that finally appears, instead of having one chromosome-
should, has two or
none
at
all.
After union with another
with the normal single chromosome present, the
ovum has either three, 21-21-21, or one, 21. The case of the three is Down's syndrome. The until recently, never
been detected.
It
fertilized
case of one had,
was suspected that the
THE SOLAR SYSTEM AND BACK
228
possession of one presented so serious a disadvantage for the de-
veloping egg that
it
never reached term. But then, at the Bethesda
Naval Medical Center half-year-old girl
was the
first
1967, a mentally-retarded three-and-a-
in
was found to have a
chromosome-21. She
single
human
discovered case of a living
being with a miss-
ing chromosome.
Cases involving other chromosomes seem
common
less
but are
turning up. Patients with a particular type of leukemia show a tiny
chromosome fragment
extra
in
their
"Philadelphia chromosome" because city.
Broken chromosomes,
normal frequency
cells.
it
was
in general, turn
This
is
called
the
located in that
first
up with
greater than
in the cells of people with certain other (not
common) diseases. The sex chromosomes,
very
too,
can be involved in aberrations.
can be formed with two X-chromosomes or none.
A
An
sperm
egg
cell
cell
can be formed with both an X- and Y-chromosome, or with
neither. In such cases, a fertilized
XXY,
or
Such rarely
XYY,
or simply
cases are not
X
ovum may be formed
that
is
or simply Y.
common, perhaps because such embryos
complete their development. Nevertheless, they have been
detected.
A person
born with an
XXY
set in his cells
has the out-
ward appearance of an underdeveloped male. On the other hand, X and XYY individuals seem to have the outward underdeveloped characteristics of a female.
The
individual
who made the headlines in Ewa Koblukowska,
such an abnormality was twenty-one-year-old Polish a
girl,
girl.
connection with tall,
muscular
She always thought of
herself as
a
and, although flat-chested, had the sexual organs of a
girl.
She was, however, an excellent athlete and the question arose as to whether she might not have some male characteristics, including larger
and stronger muscles than females have
generally. This
would be no crime, of course, but it would then be unsportsmanlike to have her compete with normal females. Her chromosomes were counted and the six doctors (three Rus-
COUNTING CHROMOSOMES sians
and three Hungarians) found themselves
announcement Naturally,
it
229
in agreement.
chromosome too many."
would be useful
methods that would cut
down on such chromosome
to devise
aberrations. Failing that,
it
certainly be advisable to avoid conditions that increase
some
The
was that there was "one
aberrations. Biologists are well acquainted with a
would
chromo-
number and
of these. Energetic radiation, for instance, will do so,
will
produce gene mutations, too. It is partly for this
reason that world public opinion bore
so heavily against nuclear
The
bomb
the open atmosphere.
tests in
radioactive particles produced
down
might not
outright, but
kill
they would slightly raise the mutation rate and increase the an-
nual production of defectives of one sort or another.
But
it
is
not radiation only that encourages mutation. There
do so— chemicals that
are certain chemicals that
chromosome likely to
replication
come
and separation.
in contact with
Human
most of the
interfere with
beings are not
particular chemicals
that chemists work with, but a few years ago there was the case of the tranquilizer thalidomide, which produced deformed babies
once
it
was given to pregnant women.
chromosome Anything ple
It
undoubtedly produced
aberrations. else?
Might
there be such a substance to which peo-
had not been exposed
till
recently,
but which was
now com-
ing into wider use?
This thought occurred to Dr. University of
New
York
Maimon M. Cohen
of the State
in Buffalo. In June, 1966, after visiting a
hippie hangout out of curiosity, he found himself wondering about
the bizarre behavior of some of them.
Were
their cellular instruc-
tions being interfered with?
His work dealt with chromosome counts so he could check. Back at his laboratory,
he began work with white blood
cells,
which
could be obtained easily and in quantity from any drop of blood.
He exposed some of them to a weak solution of LSD, then studied their chromosomes. He found they showed twice as many broken
THE SOLAR SYSTEM AND BACK
23O
and abnormal chromosomes had not been exposed
What test
to
LSD.
about exposure to
white
cells
did which
as ordinary white cells
LSD
He
body?
inside the
began to
from people who admitted having used LSD. So
did other experimenters, after the
reports
first
began
to reach the
world of science.
There seemed rather general agreement. The white
cells
of
LSD-users had unusually high numbers of broken and abnormal
chromosomes.
Was
it
only in the white
particular, did
chromosome
or was
cells,
it
in cells generally? In
aberrations take place in the sex-cells
of LSD-users to a greater extent than in non-users? If so, there
would be more defective
births
among LSD-users than among
others.
among what
wait for births
It is difficult to
still
is
segment of the population, so experimenters turned mals. Small
and, in a
amounts of
number
LSD
a small to
ani-
were injected into pregnant mice
of cases, there were serious abnormalities
and
malformations in the mouse embryos.
LSD
makes
the brain
its visible
influence felt on the nervous system and
the sake of the pleasure obtained from the
(it is for
mental aberrations and hallucinations so
it is
not surprising that
its
effect
on the seventh day of pregnancy.
it
produces that
on mice
It
is
it is
used),
most pronounced
then that the brain and
is
nervous system are being rapidly formed; and
it
brain mal-
is
formations that most frequently appear in the affected embryos.
The equivalent period —which generally comes
human pregnancies is the third week before a woman knows she is pregnant
in
and can therefore stop using the drug, This adds a new dimension to
own is
feelings against
an agent of harm
it
—since
if
she
use,
is
a user.
and strengthens
it
my
not merely an eccentricity, but
to individuals other than the user.
from the psychotic episodes cide)
it is
LSD
Quite apart
produces (up to murder and/or
and from the danger of producing a permanent
sui-
psychosis,
COUNTING CHROMOSOMES it
of
231
may increase the rate of defective births and multiply the load human tragedy upon our planet. The case is not yet proven, of course, but the indications are
that LSD-users are undergoing the equivalent of a private bath of radiation fallout.
fun
If so,
selves
may be fun—but
and higher
for their
the price can
come high
for
them-
unborn children.
Note: Since the above chapter was written (in January, 1968), chromosome anomalies has skyrocketed. It turns out
interest in
that individuals with an
handle.
They
are
tall,
XYY
combination are
difficult
people to
strong and bright and are characterized by a
who killed eight be an XYY. A murderer
tendency to rage and violence. Richard Speck, nurses in Chicago in 1966,
was acquitted
XYY
is
supposed to
in Australia in October, 1968, because
and therefore
he was an
4 per cent of the male inmates in a certain Scottish prison have turned out to be XYY. irresponsible. Nearly
There are some estimates that
many I
as
1
think
XYY
combinations
may
occur in as
man
in every 3000.
it
only reasonable to begin thinking of a routine
chromosome
is
analysis of everyone
and of every newborn
child.
UNCERTAIN, COY, AND HARD TO PLEASE
17
What
with one thing and another,
of reading of Shakespeare lately*
I
have been doing a good deal
and
I've noticed a great
many
things, including the following: Shakespeare's romantic heroines
are usually
much
and moral
strength.
Juliet
takes
superior to his heroes in intelligence, character,
strenuous
and dangerous action where Romeo (Romeo and
merely throws himself on the ground and weeps Juliet); Portia plays a difficult
and
active role
where Bassanio can
only stand on the sidelines and wring his hands (Merchant of
Venice); Benedick for Beatrice
is
a quick-witted fellow but
(Much Ado About Nothing). Nor
he is
isn't a
match
Biron a match
Orlando a match for Rosasome cases, it isn't even close. Julia is infinitely superior in every way to Proteus (Two Gentlemen of Verona) and Helena to Bertram (Ms Well That Ends Well). for Rosaline (Love's Labour's Lost) or
lind (As
The
You Like
It). In
only play in which Shakespeare seems to
chauvinism
is
The Taming
of the
Shrew and
fall
prey to male
a good case can
be
made out for something more subtle than merely a strong man beating down a strong woman— but I won't bother you about that here. *
Because I'm writing a book on the subject,
that's
why.
UNCERTAIN, COY, AND HARD TO PLEASE Yet, despite
never hear of anyone objecting to Shake-
all this, I
on the ground that he presents women
speare
never heard anyone say, "Shakespeare
On
understand women."
233
is
the contrary,
I
inaccurately.
right
all
I
have
but he doesn't
hear nothing but praise
for his heroines.
How
is
then, that Shakespeare—who, by
it,
human
has caught the
race at
its
truest
common
consent,
and most naked under
women
the probing and impersonal light of his genius— tells us anything, the superior of
are, if
so
many
ferior to
by and
large,
me
me.
It
accept their
(to put
it
me
concerns
own
inferiority.
is
my
and
I
want
and
these, I hope, will
To
to explain
be more rational
reasons for this belief.
in this
I
would
admit there are certain ineradicable physio-
let's
between
la difference!" leaves
are there
Are there
men
men and women.
(First
one to
yell
the room.)
any differences that are primarily nonphysiologi-
intellectual,
temperamental, emotional differences
and that
that you are sure of
hold for
my
in the present.
logical differences
But
is.
Woman in the future, in the light of what Woman in the past and what is happening to
begin with,
"Vive
be
human
about
has happened to
Woman
con-
as a science-fiction writer, especially, because
belief that future societies will
like to speculate
from
it
most simply) because everything concerns
rational in their treatment of 51 per cent of the
respect,
cal?
are in-
women,
matter concerns me. Well,
this
race than our present society It
women
say "us" without qualification because
I
science fiction involves future societies,
more
and yet
in all that counts,
of us nevertheless remain certain that
men.
You may wonder why cerns
men
in a broad, general
all cultures, as
will serve to distinguish
way?
I
mean
women
differences that will
the physiological differences do, and
dif-
ferences that are not the result of early training.
For instance, fined" bit, since
I
am
we
not impressed by the
all
know
"Women
are
more
re-
that mothers begin very early in the
THE SOLAR SYSTEM AND BACK
234
game
hands and
to slap little
say,
"No, no, no, nice
little girls
don't do that." myself, take the rigid position that
I,
and that the only
cultural influences
we can
never be sure about
safe distinctions
between the sexes are the physiological ones. Of
we can make
these, I recognize
two:
Most men
1.
are physically larger
and physically stronger than
most women.
Women
2.
get pregnant, bear babies,
and suckle them.
Men
don't.
What
can
seems to
me
we deduce from that this
vantage with respect to
enough
is
men
two
these
to put
differences alone?
women
in a primitive
It
at a clear disad-
hunting
society,
which
there was prior to, say, 10,000 B.C.
is all
Women,
after
would be not quite as capable at the rougher and would be further handicapped by a cer-
all,
aspects of hunting
pregnancy and certain distractions while
tain ungainliness during
taking care of infants. In a catch-as-catch-can jostle for food, she
would come up
at the rear every time.
would be convenient
It
for a
woman
to have
some man
see to
haunch
after the hunting was over and some other man didn't take it away from her. A primitive hunter would scarcely do this out of humanitarian philosophy; he would have to be bribed into it. I it
that she was thrown a
then see to
it,
suppose you're is
further, that
all
ahead of
me
in guessing that the obvious bribe
sex. I
visualize a
Man
and
Stone Age treaty of mutual assistance between
Woman—sex
for
food—and
togetherness, children are reared
as a result of this kind of
and the generations continue.*
an anthropologist named Charlotte O. Kursh long and fascinating letter that made it quite clear that I had dreadfully oversimplified the situation described here, that hunting was not the only food-source, and that questions of status were even more important than sex. Once one substituted "status-for-food" for "sex-for-food" she found she tended to agree with what followed. So, with this warning to take my anthropology with a grain of salt, let's continue. * After this article appeared,
wrote
me a
UNCERTAIN, COY, AND HARD TO PLEASE
235
don't see that any of the nobler passions can possibly have
I
had anything to do with
doubt that anything we would
this. I
recognize as "love" was present in the Stone Age, for romantic love
seems to have been a rather late invention and to be anything
but widespread even today.
once read that the Hollywood no-
(I
romantic love was invented by the medieval Arabs and
tion of
was spread
own Western
our
to
society
by the
Provencal
troubadours.)
As seem
for the concern of a father for his children, forget
definite indications that
men
it.
There
did not really understand the
connection between sexual intercourse and children until nearly historic times.
Mother
love
may have
pleasure of suckling, for instance) father love, however real
it
may
be,
Although the arrangement of sex sonable quid pro quo,
it isn't. It is
its
but is
basis in physiology (the I
strongly suspect that
cultural in origin.
for food
seems a pretty
rea-
a terribly unfair arrangement
because one side can break the agreement with impunity and the other cannot. If a
woman
punishes by withholding sex and a
by withholding food, which contrary, a
week without
food. Furthermore, a
what he wants by
sex
side will
week without
a lot easier than a
is
man
win out? Lysistrata to the
man who tires of this mutual woman can't.
strike
can take
force; a
seems to me, then, that for definite physiological reasons,
It
the original association of
man
one, with
men and women was a strictly unequal and woman in the role of
in the role of master
slave.
This
is
not to say that a clever woman, even in Stone Age times,
might not have managed to wheedle and her have her
own
way.
And we
all
know
man
cajole a
that this
is
into letting
certainly true
nowadays, but wheedling and cajolery are slave weapons.
Proud Reader, are a you
try to
man and
this,
I
what happens
letting
to your self-respect.
you,
would suggest
wheedle and cajole your boss into giving you a
wheedle and cajole a friend into see
don't see
If
raise,
or
you have your way, and
THE SOLAR SYSTEM AND BACK
236
In any master-slave relationship, the master does only that portion of the all else is
work that he
do or that the
reserved for the slave. It
duties not only slaves'
likes to
work
is
by custom but by
as unfit for free
men
slave
stern social law
the
"little-muscle."
the "big-muscle" work because he would have to and
women would
then do the "little-muscle" work. Let's face
(not always) a good deal for
this is usually
slaves*
which defines
to do.
Suppose we divide work into "big-muscle" and
Men would do
cannot do;
indeed frozen into the
men
it;
because there
is
more "little-muscle" work to do. ("Men work from sun to sun; women's work is never done," the old saying goes.) Sometimes, in fact, there is no "big-muscle" work to do at all. In that case the Indian brave sits around and watches the squaw far
work—a
situation that
and watch
is
true for
their non-Indian
course, that as
many
non-Indian braves
who
squaws work.* Their excuse
sit
of
is,
proud and gorgeous males they can scarcely be
ex-
pected to do "women's work."
The
social
apparatus of man-master and woman-slave was car-
ried right into the
most admired cultures of antiquity and was
never questioned there.
women tic
To
the Athenians of the Golden Age,
were inferior creatures, only dubiously superior to domes-
animals, and with nothing in the
cultivated Athenian,
it
seemed
way of human
virtually
rights.
self-evident
To
the
that male
homosexuality was the highest form of love, since that was the only
way
equal.
in
but so what;
As
which a human being (male, that
Of course, if
if
is)
could love an
he wanted children, he had to turn to a woman,
he wanted transportation, he turned to
for that other great culture of the past, the
his horse.
Hebrew,
it
is
quite obvious that the Bible accepts male superiority as a matter
of course. It
is
not even a subject for discussion at any point.
Adam and Eve, it has done woman's misery than any other book in history. The tale has enabled dozens of generations of men to blame everything on In fact, by introducing the story of
more
for
* Of course, if they are too chivalrous to watch a woman do all the work, they can always close their eyes. That will even give them a chance to sleep.
237
women.
It
made
has
would
men
of the
my-
in terms that a miserable sinner like
mad dogs. commandments themselves, women
In the ten
casually
are
and inanimate.
of property, animate
Exodus 20:17: "Thou
in
holy
hesitate to use in referring to
lumped with other forms says,
many
possible for a great
women
past to speak of self
it
It
shalt not covet thy neighbour's
house, thou shalt not covet thy neighbour's wife, nor his manservant, nor his maidservant, nor his ox,
that
is
Nor
nor his
ass,
nor any thing
thy neighbour's/'
New
the
is
quotations
I
Testament any
better.
can choose from, but
There are a number of
will give
I
you
this
one from
Ephesians 5:22-24: "Wives, submit yourselves unto your bands, as unto the Lord. For the husband
even as Christ
is
the wives be to their
This seems to
I
of
me
own husbands
hus-
is
the saviour of
subject unto Christ, so let
in every thing."
to aspire to a change in the social arrange-
man/woman from
master/slave to God/creature.
don't deny that there are
New
is
own
the head of the wife,
the head of the church: and he
the body. Therefore as the church
ment
is
many
passages in both the
Old and
Testaments that praise and dignify womankind. (For
ample, there
the
is
Book
of Ruth.)
The
trouble
is,
ex-
though, that in
the social history of our species, those passages of the Bible which
taught feminine wickedness and inferiority were by far the more
To the self-interest that led men to tighten the chains women was added the most formidable of religious in-
influential.
about
junctions.
The
situation has not utterly
Women in our
its
essence, even
now.
have attained a certain equality before the law—but only
own
shameful
changed in
Think how woman, however intelligent and educated, national election until 1920— despite the fact that
century, even here in the United States.
it is
that no
could vote in a
the vote was freely granted to every drunkard and moron, pro-
vided only that he happened to be male.
THE SOLAR SYSTEM AND BACK
238
women can own bodies— all the
Yet even so—though even
own
their
and hold property, and
vote,
social apparatus of inferiority
remains.
Any man can logical,
tive, refined rather
add
can't
you that a
tell
woman
intuitive rather than
is
emotional rather than reasonable, finicky rather than crea-
at mice,
a
and
Because
than vigorous. They don't understand
column of
figures, drive cars poorly, shriek
on and
so
women are men
equal share with
on and so on.
so
all
politics,
with terror
how
these things
in the
can they be allowed an
important tasks of running industry,
government, society?
Such an attitude
is self-fulfilling,
too.
We begin by teaching a young man that he women, and
this
top half of the
is
comforting for him.
human
race,
this
personal self-respect but his very
than a particular interested, she
if
man
must
a in
superior to
may
be.
notion threatens not only his
virility.
woman happens
whom
young
automatically in the
is
whatever his shortcomings
Anything that tends to disturb This means that
He
is
she
is
(for
never, for her very
be more intelligent
to
some arcane reason)
life,
reveal the fact.
No
sexual attraction can then overcome the mortal injury he receives in the very seat
On
and core of
his
the other hand, there
man
in the sight of a
self.
It is for
is
masculine pride, and she loses him.
something
woman who
that reason that a
is,
silly
infinitely relieving to a
manifestly, inferior to him-
woman
seems "cute."
The
more pronouncedly male-chauvinistic a society the more highly valued is silliness in a woman. Through long centuries, women have had to interest men somehow, if they were to achieve any economic security and social status at all, and so those who were not stupid and silly by nature had to carefully cultivate such stupidity and silliness until it came natural and they forgot they ever were intelligent. It is my feeling that all the emotional and temperamental distinctions between men and women are of cultural origin, and that
UNCERTAIN, COY, AND HARD TO PLEASE
239
they serve the important function of maintaining the
man/
woman It
master/slave arrangement.
seems to
me
that any clear look at social history shows this
and shows, moreover, that the feminine "temperament" jumps through hoops whenever that
is
necessary to suit man's con-
venience.
What was its
delicacy
ever
more feminine than Victorian womanhood, with
and modesty,
incredible refinement
to
and
its
blushes and catchings of breath,
its
constant need for the smelling
overcome a deplorable tendency to
sillier
Was
faint?
toy than the stereotype of the Victorian
Homo
ever a greater insult to the dignity of
But you can
see
why
the Victorian
there ever a
woman; was
work
when among
for her to
do
(or a rough approxIt
was
the upper classes, there was no "little-muscle"
since servants did
her do nothing. Firmly,
make-work nothings
men had
it.
men
her use her spare time in joining
Women
there
sapiens?
woman
imation of her) had to exist in the late nineteenth century. a time
its
salts
The
was
to let
have
her do nothing (except for such
embroidery and
as
alternative
in their work, or to
hack piano-playing).
were even encouraged to wear clothes that hampered
their physical
movements
to the point
where they could scarcely
walk or breathe.
What
was
left to
them, then, but a kind of ferocious boredom
that brought out the worst aspects of the
and made them
human temperament,
so unfit an object even for sex, that they were
carefully taught that sex
was
dirty
and
evil so that their
husbands
could go elsewhere for their pleasures.
But in this very same era, no one ever thought of applying the same toy-dog characteristics to the women of the lower classes. There was plenty of "little-muscle" work for them to do and since they had no time for fainting and refinement, the feminine
temperament made the necessary adjustment and they did without either fainting or refinement.
The
pioneer
women
of the
American West not only cleaned
THE SOLAR SYSTEM AND BACK
24O
house, cooked, and bore baby after baby, but they grabbed up
when
rifles
to fight off Indians
were
also hitched to the plow on such occasions as the horse
needed a
necessary.
strongly suspect they
I
or the tractor was being polished.
rest,
And
this
was
in
Victorian times.
We
see
women
just aren't
know how I
was a
then
it
them
about us even now.
it all
little
bank
There was a time
women
When
all
tellers.
Now
90 per cent of figures
and
all.
nurses were males because everyone
knew
were simply too delicate and refined for such work.
the economic necessities
made
turned out they weren't
as nurses,
it
after
(Now
all.
When
were male for that very reason. But
and apparently they can add up
balance checkbooks after
that
article of faith that
dears can't balance a checkbook.
tellers
got hard to hire male bank
are female
an
any good at even the simplest arithmetic. You
those cute
kid, all
It's
nursing
is
it
important to hire females
all
that delicate and refined
"woman's work" that
a
proud
man
wouldn't do.)
Doctors and engineers are almost always of social or economic crunch
men— until some
comes— and then
sort
the female temper-
ament makes the necessary change and, as in the Soviet Union, women become doctors and engineers in great numbers. What it amounts to is best expressed in a well-known verse by Sir Walter Scott:
O
woman!
in our hours of ease.
Uncertain, coy, and hard to please, •
•
•
When pain and anguish wring A ministering angel thou! Most women seem ful tribute to
to think this
them, but
of the fact that
I
when man
is
think that is
relaxing
the brow,
a very touching it is
and wonder-
a rather bald exhibition
he wants a toy and when he
UNCERTAIN, COY, AND HARD TO PLEASE in trouble
is
he wants a
slave
and woman
on instant
is
241 call for
either role.
What
if
ing angel?
But for
let's
pain and anguish wring her brow?
Why, not
women's
woman who
another
slip to
votes,
the male chauvinists said that this would
women had no
would merely be manipulated by by any
her minister-
the other extreme either. During the fight
wreck the nation since
priests, or
Who's
hired for the occasion.
is
political
their
feeling for politics
and
menfolks (or by their
quack with a scalpful of
curls
and a
mouthful of teeth). Feminists, on the other hand, said that their gentleness all graft,
It
when women brought
and refinement and honesty
corruption,
to the polling booth,
and war would be brought
to
an end.
You know what happened when women got the vote? Nothing. turned out that women were no stupider than men—and no
wiser, either.
What
of the future? Will
Not
basic conditions continue as they have ever since
if
sapiens
became
a species.
women
Men
gain true equality?
Homo
won't voluntarily give up their ad-
vantage. Masters never do. Sometimes they are forced to do so by
one
violent revolution of
sort or another.
forced to do so by their wise foresight of a
Sometimes they are
coming violent
revolu-
tion.
An
individual
may
up an advantage out of a mere sense of always in the minority and a group as a
give
decency, but such are
whole never does. Indeed, in the present case, the strongest proponents of the status
quo are the women themselves
They have played the
role so long they
the wrists and ankles
the chains were struck
grown
if
so used to the petty rewards
fered elbow, the smirk
be
silly)
and
leer,
would
feel chills
off.
And
about
they have
(the tipped hat, the of-
and, most of
that they won't exchange
most of them).
(at least
them
all,
the freedom to
for freedom.
Who
is
THE SOLAR SYSTEM AND BACK
242
woman who
hardest on the independent-minded
conventions? Other
women,
defies the slave-
of course, playing the fink
on behalf
men.
of
Yet things
What
was the
women? 1. Most men most women. So?
change even
will
woman's
that underlie
What
mayhem
first
are physically larger
when only
Rape
And
does
it
a
Is
and physically stronger than a crime
and
so
is
physical
women. That doesn't does keep them from being
it
game they once
men woman too
matter that
economic sense?
Does she have
is
men and
directed against
stop such practices altogether, but
the universal masculine
between
difference
essential
of that today.
even
because the basic conditions
so,
historic position are changing.
were.
are larger
and
stronger, in the
small and
weak
to earn a living?
to crawl into the protecting neck-clutch of a male,
however stupid or
haunch of the
he may be, for the equivalent of the
distasteful
kill?
Nonsense! "Big-muscle" jobs are steadily disappearing and only "little-muscle" jobs are left.
push buttons and
let
We
don't dig ditches any more,
machines dig ditches. The world
computerized and there
is
nothing a
man
is
we
being
can do in the way of
pushing paper, sorting cards, and twiddling contacts, that a
woman
can't
do
just as well.
In fact, littleness
may be
at a
premium. Smaller and slenderer
may be just what is wanted. More and more, women will learn
fingers
sex
and love
nothing that quickly do
for love,
and nevermore
will dignify sex
they need only offer sex for sex for food.
more than
this
I
can think of
change, or more
away with the degrading master/slave existence of "the
double standard."
But how about the second 2.
Women
don't.
difference:
get pregnant, bear babies,
and suckle them.
Men
UNCERTAIN, COY, AND HARD TO PLEASE frequently hear
I
tell
that
women
have a "nest-building"
they really want to take care of a
stinct, that
Maybe
themselves for his sake.
so,
243 in-
man and immolate
under conditions
as they used
But how about now?
to be.
With
the population explosion becoming more and more of a
mankind, we
cliff-hanger for all
before the end of the cen-
will,
have evolved a new attitude toward babies or our culture
tury,
will die. It will
become
The
babies. will lift
nomic
mean even more than
will
Thanks
pressure.
to the
pill,
without the abandonment of
lifted
become
stifling social pressure to
and that
woman
perfectly all right for a
women
This doesn't mean
not to have
a "wife
and mother"
the lifting of the eco-
the burden of babies can be sex.
won't have babies;
it
means merely
they won't have to have babies.
In
female slavery and the population explosion
fact, I feel that
go hand in hand. Keep a
man
will feel safe
woman
in subjection
to keep her "barefoot
is
and the only way a
and pregnant."
If
she
has nothing to do except undignified and repetitive labor, a
woman
will
want baby
after
baby
as the only escape to
something
else.
On
the other hand,
explosion will stop of sacrifice their
say
freedom
"No" too
tried,
but
where the
make women truly free and the population its own accord. Few women would want to for the sake of
must be
it
completely free for the
cycles
I
babies.
significant that the birth
social position of
women
In the twenty-first century, then,
Nor am
numerous
quickly; feminine freedom has never
first
is
I
rate
And
don't
been
truly
is
highest
lowest.
predict that
women
will
be
time in the history of the species.
afraid of the counter-prediction that all things go in
and that the
pation will give Effects can
way
be
clearly visible trend
toward feminine emanci-
to a swing back to a kind of neo-Victorianism.
cyclic,
yes—but only
if
causes are cyclic,
and the
THE SOLAR SYSTEM AND BACK
244
thermonu-
basic causes here are non-cyclic, barring world-wide clear war.
In order for the pendulum to swing back toward feminine slavery, there
that only
would have
men
starvation without a
be an increase in "big-muscle jobs"
to
Women
could do.
man
work
to
must begin once more
to fear
them. Well, do you think
for
the present trend toward computerization and social security will reverse itself short of global catastrophe? Honestly?
In order for the pendulum to swing back, there would have to
be a continuation of the desire
way
dren. There's no other
for large families
of keeping
and
women
lots of chil-
contented with
her slavery on a large scale (or too busy to think about
it, which same thing). Given our present population explosion and the situation as it will be by 2000, do you honestly expect women to be put to work breeding baby after baby?
amounts
to the
So the trend toward woman's freedom There's the beginning of
Do
it
right
is
irreversible.
now and
it is
well established.
you think that the present era of increasing sexual permissive-
ness (almost everywhere in the world)
down
in our
moral
fiber
and that
a
is
little
just a
temporary break-
government action
will
restore the stern virtues of our ancestors?
Don't you believe will
continue to be
it.
Sex has been divorced from babies, and
so, since sex can't possibly
babies can't possibly be encouraged.
but the "sexual revolution"
Or
Vote
for
whom
man.
you please
will continue.
take even something so apparently trivial as the
hairiness in
it
be suppressed and
new
fad of
grown a pair of absolutely magnificent
(I've just
change in
sideburns myself.)
Sure,
really stands for is
the breakdown of
it
will
details,
but what
trivial distinctions
it
between
the sexes. It is
indeed this which disturbs the conventional. Over and
over, I hear
them complain that some
looks just like a
any more!"
girl.
And
then they
say,
particular long-haired
"You
can't
tell
boy
them apart
UNCERTAIN, COY, AND HARD TO PLEASE This always makes
boy from a
me wonder why
where the sex makes a
in view
neer or an After
is
if it
were
is
You
make
Catholic, Protestant, or
or stupid.
important to
really
use of Nature's distinction? That
tell
the sexes apart at
why not
the difference
is
sometimes extreme.
Well, then, should
all
who
Any change
beards.
if
women,
poor thing,
wife,
men grow
beards? Yet the very same con-
unsettles them,
so
man,
also object to
when change becomes
must be ignored.
men and long hair for men and skirts for women,
this fetish of short hair for
or, for
that matter, pants for
men and
shirts for
(My
blouses for
women?
Why a set of artificial Why the sense of
tinctions to exaggerate the natural ones?
turbance
Can
it
when the
No
dis-
dis-
distinctions are blurred?
be that the loud and gaudy distinction of dress and hair
between the two sexes ship?
On
women;
she tried.)
object to long hair on a
necessary, conventional people
But why
not long hair since both
always have more facial hair than
couldn't grow sideburns even
ventional people
is
grow hair of approximately equal length.
men
the other hand,
a
can't tell at a
the distance of several blocks with one quick glance,
sexes in all cultures
tell
a piano player or a poker player, an engi-
artist, intelligent
all,
so important to
difference.
glance whether a particular person Jew; whether he/she
it is
one has some personal object
at a glance, unless
girl
245
is
another sign of the master-slave relation-
master wants to be mistaken for a slave at any distance,
or have a slave mistaken for a master, either. In slave societies, slaves are always carefully distinguished
Manchus ruled
(by a pigtail
ruled China, by a yellow Star of David
when the Nazis
Germany, and so on). We ourselves tend to most conspicuous non-female slaves had a
since our
skin color
and required very
little else
In the society of sexual equality that
be a blurring of that
is
already
artificial distinctions
on the way. But
so
to is
when the forget this distinctive
mark them. coming, then, there
between the what?
A
will
sexes, a blurring
particular
boy
will
THE SOLAR SYSTEM AND BACK
246
know who is
his particular girl
is
and
vice versa,
and
if
someone
else
not part of the relationship what does he/she care which
is
which? I
say
it
pened I
we can't beat the trend and we should may even be the most wonderful thing
say
to
it.
I
that has ever hap-
mankind.
think the Greeks were right in a
to love an equal.
when we
therefore join
And
if
way and
that be so,
that
why not
heterosexuals can have love at
its
it is
much
better
hasten the time
best?
N3